Add option to disable real-time updates in web UI (#9984)

Fix #9031
Fix #7913

20 files changed, 181 insertions, 70 deletions

diff --git a/app/controllers/settings/preferences_controller.rb b/app/controllers/settings/preferences_controller.rb
index 0a5c14cca..742c97cdb 100644
--- a/app/controllers/settings/preferences_controller.rb
+++ b/app/controllers/settings/preferences_controller.rb
@@ -55,6 +55,7 @@ class Settings::PreferencesController < Settings::BaseController
       :setting_show_application,
       :setting_advanced_layout,
       :setting_use_blurhash,
+      :setting_use_pending_items,
       notification_emails: %i(follow follow_request reblog favourite mention digest report pending_account),
       interactions: %i(must_be_follower must_be_following must_be_following_dm)
     )
diff --git a/app/javascript/mastodon/actions/notifications.js b/app/javascript/mastodon/actions/notifications.js
index 56c952cb0..d92d972bc 100644
--- a/app/javascript/mastodon/actions/notifications.js
+++ b/app/javascript/mastodon/actions/notifications.js
@@ -12,6 +12,8 @@ import { defineMessages } from 'react-intl';
 import { List as ImmutableList } from 'immutable';
 import { unescapeHTML } from '../utils/html';
 import { getFiltersRegex } from '../selectors';
+import { usePendingItems as preferPendingItems } from 'mastodon/initial_state';
+import compareId from 'mastodon/compare_id';
 
 export const NOTIFICATIONS_UPDATE      = 'NOTIFICATIONS_UPDATE';
 export const NOTIFICATIONS_UPDATE_NOOP = 'NOTIFICATIONS_UPDATE_NOOP';
@@ -22,8 +24,9 @@ export const NOTIFICATIONS_EXPAND_FAIL    = 'NOTIFICATIONS_EXPAND_FAIL';
 
 export const NOTIFICATIONS_FILTER_SET = 'NOTIFICATIONS_FILTER_SET';
 
-export const NOTIFICATIONS_CLEAR      = 'NOTIFICATIONS_CLEAR';
-export const NOTIFICATIONS_SCROLL_TOP = 'NOTIFICATIONS_SCROLL_TOP';
+export const NOTIFICATIONS_CLEAR        = 'NOTIFICATIONS_CLEAR';
+export const NOTIFICATIONS_SCROLL_TOP   = 'NOTIFICATIONS_SCROLL_TOP';
+export const NOTIFICATIONS_LOAD_PENDING = 'NOTIFICATIONS_LOAD_PENDING';
 
 defineMessages({
   mention: { id: 'notification.mention', defaultMessage: '{name} mentioned you' },
@@ -38,6 +41,10 @@ const fetchRelatedRelationships = (dispatch, notifications) => {
   }
 };
 
+export const loadPending = () => ({
+  type: NOTIFICATIONS_LOAD_PENDING,
+});
+
 export function updateNotifications(notification, intlMessages, intlLocale) {
   return (dispatch, getState) => {
     const showInColumn = getState().getIn(['settings', 'notifications', 'shows', notification.type], true);
@@ -69,6 +76,7 @@ export function updateNotifications(notification, intlMessages, intlLocale) {
       dispatch({
         type: NOTIFICATIONS_UPDATE,
         notification,
+        usePendingItems: preferPendingItems,
         meta: (playSound && !filtered) ? { sound: 'boop' } : undefined,
       });
 
@@ -122,10 +130,19 @@ export function expandNotifications({ maxId } = {}, done = noOp) {
         : excludeTypesFromFilter(activeFilter),
     };
 
-    if (!maxId && notifications.get('items').size > 0) {
-      params.since_id = notifications.getIn(['items', 0, 'id']);
+    if (!params.max_id && (notifications.get('items', ImmutableList()).size + notifications.get('pendingItems', ImmutableList()).size) > 0) {
+      const a = notifications.getIn(['pendingItems', 0, 'id']);
+      const b = notifications.getIn(['items', 0, 'id']);
+
+      if (a && b && compareId(a, b) > 0) {
+        params.since_id = a;
+      } else {
+        params.since_id = b || a;
+      }
     }
 
+    const isLoadingRecent = !!params.since_id;
+
     dispatch(expandNotificationsRequest(isLoadingMore));
 
     api(getState).get('/api/v1/notifications', { params }).then(response => {
@@ -134,7 +151,7 @@ export function expandNotifications({ maxId } = {}, done = noOp) {
       dispatch(importFetchedAccounts(response.data.map(item => item.account)));
       dispatch(importFetchedStatuses(response.data.map(item => item.status).filter(status => !!status)));
 
-      dispatch(expandNotificationsSuccess(response.data, next ? next.uri : null, isLoadingMore));
+      dispatch(expandNotificationsSuccess(response.data, next ? next.uri : null, isLoadingMore, isLoadingRecent && preferPendingItems));
       fetchRelatedRelationships(dispatch, response.data);
       done();
     }).catch(error => {
@@ -151,11 +168,12 @@ export function expandNotificationsRequest(isLoadingMore) {
   };
 };
 
-export function expandNotificationsSuccess(notifications, next, isLoadingMore) {
+export function expandNotificationsSuccess(notifications, next, isLoadingMore, usePendingItems) {
   return {
     type: NOTIFICATIONS_EXPAND_SUCCESS,
     notifications,
     next,
+    usePendingItems,
     skipLoading: !isLoadingMore,
   };
 };
diff --git a/app/javascript/mastodon/actions/timelines.js b/app/javascript/mastodon/actions/timelines.js
index 06c21b96b..7eeba2aa7 100644
--- a/app/javascript/mastodon/actions/timelines.js
+++ b/app/javascript/mastodon/actions/timelines.js
@@ -1,6 +1,8 @@
 import { importFetchedStatus, importFetchedStatuses } from './importer';
-import api, { getLinks } from '../api';
+import api, { getLinks } from 'mastodon/api';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
+import compareId from 'mastodon/compare_id';
+import { usePendingItems as preferPendingItems } from 'mastodon/initial_state';
 
 export const TIMELINE_UPDATE  = 'TIMELINE_UPDATE';
 export const TIMELINE_DELETE  = 'TIMELINE_DELETE';
@@ -10,10 +12,15 @@ export const TIMELINE_EXPAND_REQUEST = 'TIMELINE_EXPAND_REQUEST';
 export const TIMELINE_EXPAND_SUCCESS = 'TIMELINE_EXPAND_SUCCESS';
 export const TIMELINE_EXPAND_FAIL    = 'TIMELINE_EXPAND_FAIL';
 
-export const TIMELINE_SCROLL_TOP = 'TIMELINE_SCROLL_TOP';
+export const TIMELINE_SCROLL_TOP   = 'TIMELINE_SCROLL_TOP';
+export const TIMELINE_LOAD_PENDING = 'TIMELINE_LOAD_PENDING';
+export const TIMELINE_DISCONNECT   = 'TIMELINE_DISCONNECT';
+export const TIMELINE_CONNECT      = 'TIMELINE_CONNECT';
 
-export const TIMELINE_CONNECT    = 'TIMELINE_CONNECT';
-export const TIMELINE_DISCONNECT = 'TIMELINE_DISCONNECT';
+export const loadPending = timeline => ({
+  type: TIMELINE_LOAD_PENDING,
+  timeline,
+});
 
 export function updateTimeline(timeline, status, accept) {
   return dispatch => {
@@ -27,6 +34,7 @@ export function updateTimeline(timeline, status, accept) {
       type: TIMELINE_UPDATE,
       timeline,
       status,
+      usePendingItems: preferPendingItems,
     });
   };
 };
@@ -71,8 +79,15 @@ export function expandTimeline(timelineId, path, params = {}, done = noOp) {
       return;
     }
 
-    if (!params.max_id && !params.pinned && timeline.get('items', ImmutableList()).size > 0) {
-      params.since_id = timeline.getIn(['items', 0]);
+    if (!params.max_id && !params.pinned && (timeline.get('items', ImmutableList()).size + timeline.get('pendingItems', ImmutableList()).size) > 0) {
+      const a = timeline.getIn(['pendingItems', 0]);
+      const b = timeline.getIn(['items', 0]);
+
+      if (a && b && compareId(a, b) > 0) {
+        params.since_id = a;
+      } else {
+        params.since_id = b || a;
+      }
     }
 
     const isLoadingRecent = !!params.since_id;
@@ -82,7 +97,7 @@ export function expandTimeline(timelineId, path, params = {}, done = noOp) {
     api(getState).get(path, { params }).then(response => {
       const next = getLinks(response).refs.find(link => link.rel === 'next');
       dispatch(importFetchedStatuses(response.data));
-      dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.code === 206, isLoadingRecent, isLoadingMore));
+      dispatch(expandTimelineSuccess(timelineId, response.data, next ? next.uri : null, response.code === 206, isLoadingRecent, isLoadingMore, isLoadingRecent && preferPendingItems));
       done();
     }).catch(error => {
       dispatch(expandTimelineFail(timelineId, error, isLoadingMore));
@@ -115,7 +130,7 @@ export function expandTimelineRequest(timeline, isLoadingMore) {
   };
 };
 
-export function expandTimelineSuccess(timeline, statuses, next, partial, isLoadingRecent, isLoadingMore) {
+export function expandTimelineSuccess(timeline, statuses, next, partial, isLoadingRecent, isLoadingMore, usePendingItems) {
   return {
     type: TIMELINE_EXPAND_SUCCESS,
     timeline,
@@ -123,6 +138,7 @@ export function expandTimelineSuccess(timeline, statuses, next, partial, isLoadi
     next,
     partial,
     isLoadingRecent,
+    usePendingItems,
     skipLoading: !isLoadingMore,
   };
 };
@@ -151,9 +167,8 @@ export function connectTimeline(timeline) {
   };
 };
 
-export function disconnectTimeline(timeline) {
-  return {
-    type: TIMELINE_DISCONNECT,
-    timeline,
-  };
-};
+export const disconnectTimeline = timeline => ({
+  type: TIMELINE_DISCONNECT,
+  timeline,
+  usePendingItems: preferPendingItems,
+});
diff --git a/app/javascript/mastodon/compare_id.js b/app/javascript/mastodon/compare_id.js
index aaff66481..66cf51c4b 100644
--- a/app/javascript/mastodon/compare_id.js
+++ b/app/javascript/mastodon/compare_id.js
@@ -1,10 +1,11 @@
-export default function compareId(id1, id2) {
+export default function compareId (id1, id2) {
   if (id1 === id2) {
     return 0;
   }
+
   if (id1.length === id2.length) {
     return id1 > id2 ? 1 : -1;
   } else {
     return id1.length > id2.length ? 1 : -1;
   }
-}
+};
diff --git a/app/javascript/mastodon/components/load_pending.js b/app/javascript/mastodon/components/load_pending.js
new file mode 100644
index 000000000..7e2702403
--- /dev/null
+++ b/app/javascript/mastodon/components/load_pending.js
@@ -0,0 +1,22 @@
+import React from 'react';
+import { FormattedMessage } from 'react-intl';
+import PropTypes from 'prop-types';
+
+export default class LoadPending extends React.PureComponent {
+
+  static propTypes = {
+    onClick: PropTypes.func,
+    count: PropTypes.number,
+  }
+
+  render() {
+    const { count } = this.props;
+
+    return (
+      <button className='load-more load-gap' onClick={this.props.onClick}>
+        <FormattedMessage id='load_pending' defaultMessage='{count, plural, one {# new item} other {# new items}}' values={{ count }} />
+      </button>
+    );
+  }
+
+}
diff --git a/app/javascript/mastodon/components/scrollable_list.js b/app/javascript/mastodon/components/scrollable_list.js
index 0376cf85a..553c16352 100644
--- a/app/javascript/mastodon/components/scrollable_list.js
+++ b/app/javascript/mastodon/components/scrollable_list.js
@@ -3,6 +3,7 @@ import { ScrollContainer } from 'react-router-scroll-4';
 import PropTypes from 'prop-types';
 import IntersectionObserverArticleContainer from '../containers/intersection_observer_article_container';
 import LoadMore from './load_more';
+import LoadPending from './load_pending';
 import IntersectionObserverWrapper from '../features/ui/util/intersection_observer_wrapper';
 import { throttle } from 'lodash';
 import { List as ImmutableList } from 'immutable';
@@ -21,6 +22,7 @@ export default class ScrollableList extends PureComponent {
   static propTypes = {
     scrollKey: PropTypes.string.isRequired,
     onLoadMore: PropTypes.func,
+    onLoadPending: PropTypes.func,
     onScrollToTop: PropTypes.func,
     onScroll: PropTypes.func,
     trackScroll: PropTypes.bool,
@@ -28,6 +30,7 @@ export default class ScrollableList extends PureComponent {
     isLoading: PropTypes.bool,
     showLoading: PropTypes.bool,
     hasMore: PropTypes.bool,
+    numPending: PropTypes.number,
     prepend: PropTypes.node,
     alwaysPrepend: PropTypes.bool,
     emptyMessage: PropTypes.node,
@@ -225,12 +228,18 @@ export default class ScrollableList extends PureComponent {
     this.props.onLoadMore();
   }
 
+  handleLoadPending = e => {
+    e.preventDefault();
+    this.props.onLoadPending();
+  }
+
   render () {
-    const { children, scrollKey, trackScroll, shouldUpdateScroll, showLoading, isLoading, hasMore, prepend, alwaysPrepend, emptyMessage, onLoadMore } = this.props;
+    const { children, scrollKey, trackScroll, shouldUpdateScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, emptyMessage, onLoadMore } = this.props;
     const { fullscreen } = this.state;
     const childrenCount = React.Children.count(children);
 
     const loadMore     = (hasMore && onLoadMore) ? <LoadMore visible={!isLoading} onClick={this.handleLoadMore} /> : null;
+    const loadPending  = (numPending > 0) ? <LoadPending count={numPending} onClick={this.handleLoadPending} /> : null;
     let scrollableArea = null;
 
     if (showLoading) {
@@ -251,6 +260,8 @@ export default class ScrollableList extends PureComponent {
           <div role='feed' className='item-list'>
             {prepend}
 
+            {loadPending}
+
             {React.Children.map(this.props.children, (child, index) => (
               <IntersectionObserverArticleContainer
                 key={child.key}
diff --git a/app/javascript/mastodon/features/community_timeline/components/column_settings.js b/app/javascript/mastodon/features/community_timeline/components/column_settings.js
index 8250190a7..0cb6db883 100644
--- a/app/javascript/mastodon/features/community_timeline/components/column_settings.js
+++ b/app/javascript/mastodon/features/community_timeline/components/column_settings.js
@@ -20,7 +20,7 @@ class ColumnSettings extends React.PureComponent {
     return (
       <div>
         <div className='column-settings__row'>
-          <SettingToggle settings={settings} settingPath={['other', 'onlyMedia']} onChange={onChange} label={<FormattedMessage id='community.column_settings.media_only' defaultMessage='Media Only' />} />
+          <SettingToggle settings={settings} settingPath={['other', 'onlyMedia']} onChange={onChange} label={<FormattedMessage id='community.column_settings.media_only' defaultMessage='Media only' />} />
         </div>
       </div>
     );
diff --git a/app/javascript/mastodon/features/notifications/components/setting_toggle.js b/app/javascript/mastodon/features/notifications/components/setting_toggle.js
index 7aec16d2e..e6f593ef8 100644
--- a/app/javascript/mastodon/features/notifications/components/setting_toggle.js
+++ b/app/javascript/mastodon/features/notifications/components/setting_toggle.js
@@ -11,6 +11,7 @@ export default class SettingToggle extends React.PureComponent {
     settingPath: PropTypes.array.isRequired,
     label: PropTypes.node.isRequired,
     onChange: PropTypes.func.isRequired,
+    defaultValue: PropTypes.bool,
   }
 
   onChange = ({ target }) => {
@@ -18,12 +19,12 @@ export default class SettingToggle extends React.PureComponent {
   }
 
   render () {
-    const { prefix, settings, settingPath, label } = this.props;
+    const { prefix, settings, settingPath, label, defaultValue } = this.props;
     const id = ['setting-toggle', prefix, ...settingPath].filter(Boolean).join('-');
 
     return (
       <div className='setting-toggle'>
-        <Toggle id={id} checked={settings.getIn(settingPath)} onChange={this.onChange} onKeyDown={this.onKeyDown} />
+        <Toggle id={id} checked={settings.getIn(settingPath, defaultValue)} onChange={this.onChange} onKeyDown={this.onKeyDown} />
         <label htmlFor={id} className='setting-toggle__label'>{label}</label>
       </div>
     );
diff --git a/app/javascript/mastodon/features/notifications/index.js b/app/javascript/mastodon/features/notifications/index.js
index 006c45657..df4ad6f2a 100644
--- a/app/javascript/mastodon/features/notifications/index.js
+++ b/app/javascript/mastodon/features/notifications/index.js
@@ -4,7 +4,7 @@ import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import Column from '../../components/column';
 import ColumnHeader from '../../components/column_header';
-import { expandNotifications, scrollTopNotifications } from '../../actions/notifications';
+import { expandNotifications, scrollTopNotifications, loadPending } from '../../actions/notifications';
 import { addColumn, removeColumn, moveColumn } from '../../actions/columns';
 import NotificationContainer from './containers/notification_container';
 import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
@@ -41,6 +41,7 @@ const mapStateToProps = state => ({
   isLoading: state.getIn(['notifications', 'isLoading'], true),
   isUnread: state.getIn(['notifications', 'unread']) > 0,
   hasMore: state.getIn(['notifications', 'hasMore']),
+  numPending: state.getIn(['notifications', 'pendingItems'], ImmutableList()).size,
 });
 
 export default @connect(mapStateToProps)
@@ -58,6 +59,7 @@ class Notifications extends React.PureComponent {
     isUnread: PropTypes.bool,
     multiColumn: PropTypes.bool,
     hasMore: PropTypes.bool,
+    numPending: PropTypes.number,
   };
 
   static defaultProps = {
@@ -80,6 +82,10 @@ class Notifications extends React.PureComponent {
     this.props.dispatch(expandNotifications({ maxId: last && last.get('id') }));
   }, 300, { leading: true });
 
+  handleLoadPending = () => {
+    this.props.dispatch(loadPending());
+  };
+
   handleScrollToTop = debounce(() => {
     this.props.dispatch(scrollTopNotifications(true));
   }, 100);
@@ -136,7 +142,7 @@ class Notifications extends React.PureComponent {
   }
 
   render () {
-    const { intl, notifications, shouldUpdateScroll, isLoading, isUnread, columnId, multiColumn, hasMore, showFilterBar } = this.props;
+    const { intl, notifications, shouldUpdateScroll, isLoading, isUnread, columnId, multiColumn, hasMore, numPending, showFilterBar } = this.props;
     const pinned = !!columnId;
     const emptyMessage = <FormattedMessage id='empty_column.notifications' defaultMessage="You don't have any notifications yet. Interact with others to start the conversation." />;
 
@@ -178,8 +184,10 @@ class Notifications extends React.PureComponent {
         isLoading={isLoading}
         showLoading={isLoading && notifications.size === 0}
         hasMore={hasMore}
+        numPending={numPending}
         emptyMessage={emptyMessage}
         onLoadMore={this.handleLoadOlder}
+        onLoadPending={this.handleLoadPending}
         onScrollToTop={this.handleScrollToTop}
         onScroll={this.handleScroll}
         shouldUpdateScroll={shouldUpdateScroll}
diff --git a/app/javascript/mastodon/features/ui/containers/status_list_container.js b/app/javascript/mastodon/features/ui/containers/status_list_container.js
index 3df5b7bea..7b8eb652b 100644
--- a/app/javascript/mastodon/features/ui/containers/status_list_container.js
+++ b/app/javascript/mastodon/features/ui/containers/status_list_container.js
@@ -1,6 +1,6 @@
 import { connect } from 'react-redux';
 import StatusList from '../../../components/status_list';
-import { scrollTopTimeline } from '../../../actions/timelines';
+import { scrollTopTimeline, loadPending } from '../../../actions/timelines';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
 import { createSelector } from 'reselect';
 import { debounce } from 'lodash';
@@ -37,6 +37,7 @@ const makeMapStateToProps = () => {
     isLoading: state.getIn(['timelines', timelineId, 'isLoading'], true),
     isPartial: state.getIn(['timelines', timelineId, 'isPartial'], false),
     hasMore:   state.getIn(['timelines', timelineId, 'hasMore']),
+    numPending: state.getIn(['timelines', timelineId, 'pendingItems'], ImmutableList()).size,
   });
 
   return mapStateToProps;
@@ -52,6 +53,8 @@ const mapDispatchToProps = (dispatch, { timelineId }) => ({
     dispatch(scrollTopTimeline(timelineId, false));
   }, 100),
 
+  onLoadPending: () => dispatch(loadPending(timelineId)),
+
 });
 
 export default connect(makeMapStateToProps, mapDispatchToProps)(StatusList);
diff --git a/app/javascript/mastodon/initial_state.js b/app/javascript/mastodon/initial_state.js
index f0f131ff5..cb2ccc7c4 100644
--- a/app/javascript/mastodon/initial_state.js
+++ b/app/javascript/mastodon/initial_state.js
@@ -21,5 +21,6 @@ export const profile_directory = getMeta('profile_directory');
 export const isStaff = getMeta('is_staff');
 export const forceSingleColumn = !getMeta('advanced_layout');
 export const useBlurhash = getMeta('use_blurhash');
+export const usePendingItems = getMeta('use_pending_items');
 
 export default initialState;
diff --git a/app/javascript/mastodon/reducers/notifications.js b/app/javascript/mastodon/reducers/notifications.js
index 4d9604de9..e94a4946b 100644
--- a/app/javascript/mastodon/reducers/notifications.js
+++ b/app/javascript/mastodon/reducers/notifications.js
@@ -6,6 +6,7 @@ import {
   NOTIFICATIONS_FILTER_SET,
   NOTIFICATIONS_CLEAR,
   NOTIFICATIONS_SCROLL_TOP,
+  NOTIFICATIONS_LOAD_PENDING,
 } from '../actions/notifications';
 import {
   ACCOUNT_BLOCK_SUCCESS,
@@ -16,6 +17,7 @@ import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
 import compareId from '../compare_id';
 
 const initialState = ImmutableMap({
+  pendingItems: ImmutableList(),
   items: ImmutableList(),
   hasMore: true,
   top: false,
@@ -31,7 +33,11 @@ const notificationToMap = notification => ImmutableMap({
   status: notification.status ? notification.status.id : null,
 });
 
-const normalizeNotification = (state, notification) => {
+const normalizeNotification = (state, notification, usePendingItems) => {
+  if (usePendingItems) {
+    return state.update('pendingItems', list => list.unshift(notificationToMap(notification)));
+  }
+
   const top = state.get('top');
 
   if (!top) {
@@ -47,7 +53,7 @@ const normalizeNotification = (state, notification) => {
   });
 };
 
-const expandNormalizedNotifications = (state, notifications, next) => {
+const expandNormalizedNotifications = (state, notifications, next, usePendingItems) => {
   let items = ImmutableList();
 
   notifications.forEach((n, i) => {
@@ -56,7 +62,7 @@ const expandNormalizedNotifications = (state, notifications, next) => {
 
   return state.withMutations(mutable => {
     if (!items.isEmpty()) {
-      mutable.update('items', list => {
+      mutable.update(usePendingItems ? 'pendingItems' : 'items', list => {
         const lastIndex = 1 + list.findLastIndex(
           item => item !== null && (compareId(item.get('id'), items.last().get('id')) > 0 || item.get('id') === items.last().get('id'))
         );
@@ -78,7 +84,8 @@ const expandNormalizedNotifications = (state, notifications, next) => {
 };
 
 const filterNotifications = (state, relationship) => {
-  return state.update('items', list => list.filterNot(item => item !== null && item.get('account') === relationship.id));
+  const helper = list => list.filterNot(item => item !== null && item.get('account') === relationship.id);
+  return state.update('items', helper).update('pendingItems', helper);
 };
 
 const updateTop = (state, top) => {
@@ -90,34 +97,37 @@ const updateTop = (state, top) => {
 };
 
 const deleteByStatus = (state, statusId) => {
-  return state.update('items', list => list.filterNot(item => item !== null && item.get('status') === statusId));
+  const helper = list => list.filterNot(item => item !== null && item.get('status') === statusId);
+  return state.update('items', helper).update('pendingItems', helper);
 };
 
 export default function notifications(state = initialState, action) {
   switch(action.type) {
+  case NOTIFICATIONS_LOAD_PENDING:
+    return state.update('items', list => state.get('pendingItems').concat(list.take(40))).set('pendingItems', ImmutableList()).set('unread', 0);
   case NOTIFICATIONS_EXPAND_REQUEST:
     return state.set('isLoading', true);
   case NOTIFICATIONS_EXPAND_FAIL:
     return state.set('isLoading', false);
   case NOTIFICATIONS_FILTER_SET:
-    return state.set('items', ImmutableList()).set('hasMore', true);
+    return state.set('items', ImmutableList()).set('pendingItems', ImmutableList()).set('hasMore', true);
   case NOTIFICATIONS_SCROLL_TOP:
     return updateTop(state, action.top);
   case NOTIFICATIONS_UPDATE:
-    return normalizeNotification(state, action.notification);
+    return normalizeNotification(state, action.notification, action.usePendingItems);
   case NOTIFICATIONS_EXPAND_SUCCESS:
-    return expandNormalizedNotifications(state, action.notifications, action.next);
+    return expandNormalizedNotifications(state, action.notifications, action.next, action.usePendingItems);
   case ACCOUNT_BLOCK_SUCCESS:
     return filterNotifications(state, action.relationship);
   case ACCOUNT_MUTE_SUCCESS:
     return action.relationship.muting_notifications ? filterNotifications(state, action.relationship) : state;
   case NOTIFICATIONS_CLEAR:
-    return state.set('items', ImmutableList()).set('hasMore', false);
+    return state.set('items', ImmutableList()).set('pendingItems', ImmutableList()).set('hasMore', false);
   case TIMELINE_DELETE:
     return deleteByStatus(state, action.id);
   case TIMELINE_DISCONNECT:
     return action.timeline === 'home' ?
-      state.update('items', items => items.first() ? items.unshift(null) : items) :
+      state.update(action.usePendingItems ? 'pendingItems' : 'items', items => items.first() ? items.unshift(null) : items) :
       state;
   default:
     return state;
diff --git a/app/javascript/mastodon/reducers/settings.js b/app/javascript/mastodon/reducers/settings.js
index a0eea137f..033bfc999 100644
--- a/app/javascript/mastodon/reducers/settings.js
+++ b/app/javascript/mastodon/reducers/settings.js
@@ -10,8 +10,6 @@ import uuid from '../uuid';
 const initialState = ImmutableMap({
   saved: true,
 
-  onboarded: false,
-
   skinTone: 1,
 
   home: ImmutableMap({
@@ -74,10 +72,6 @@ const initialState = ImmutableMap({
       body: '',
     }),
   }),
-
-  trends: ImmutableMap({
-    show: true,
-  }),
 });
 
 const defaultColumns = fromJS([
diff --git a/app/javascript/mastodon/reducers/timelines.js b/app/javascript/mastodon/reducers/timelines.js
index 309a95a19..0b036f5fe 100644
--- a/app/javascript/mastodon/reducers/timelines.js
+++ b/app/javascript/mastodon/reducers/timelines.js
@@ -8,6 +8,7 @@ import {
   TIMELINE_SCROLL_TOP,
   TIMELINE_CONNECT,
   TIMELINE_DISCONNECT,
+  TIMELINE_LOAD_PENDING,
 } from '../actions/timelines';
 import {
   ACCOUNT_BLOCK_SUCCESS,
@@ -25,10 +26,11 @@ const initialTimeline = ImmutableMap({
   top: true,
   isLoading: false,
   hasMore: true,
+  pendingItems: ImmutableList(),
   items: ImmutableList(),
 });
 
-const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, isLoadingRecent) => {
+const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, isLoadingRecent, usePendingItems) => {
   return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
     mMap.set('isLoading', false);
     mMap.set('isPartial', isPartial);
@@ -38,7 +40,7 @@ const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, is
     if (timeline.endsWith(':pinned')) {
       mMap.set('items', statuses.map(status => status.get('id')));
     } else if (!statuses.isEmpty()) {
-      mMap.update('items', ImmutableList(), oldIds => {
+      mMap.update(usePendingItems ? 'pendingItems' : 'items', ImmutableList(), oldIds => {
         const newIds = statuses.map(status => status.get('id'));
 
         const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
@@ -57,7 +59,15 @@ const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial, is
   }));
 };
 
-const updateTimeline = (state, timeline, status) => {
+const updateTimeline = (state, timeline, status, usePendingItems) => {
+  if (usePendingItems) {
+    if (state.getIn([timeline, 'pendingItems'], ImmutableList()).includes(status.get('id')) || state.getIn([timeline, 'items'], ImmutableList()).includes(status.get('id'))) {
+      return state;
+    }
+
+    return state.update(timeline, initialTimeline, map => map.update('pendingItems', list => list.unshift(status.get('id'))));
+  }
+
   const top        = state.getIn([timeline, 'top']);
   const ids        = state.getIn([timeline, 'items'], ImmutableList());
   const includesId = ids.includes(status.get('id'));
@@ -78,8 +88,10 @@ const updateTimeline = (state, timeline, status) => {
 
 const deleteStatus = (state, id, accountId, references, exclude_account = null) => {
   state.keySeq().forEach(timeline => {
-    if (exclude_account === null || (timeline !== `account:${exclude_account}` && !timeline.startsWith(`account:${exclude_account}:`)))
-      state = state.updateIn([timeline, 'items'], list => list.filterNot(item => item === id));
+    if (exclude_account === null || (timeline !== `account:${exclude_account}` && !timeline.startsWith(`account:${exclude_account}:`))) {
+      const helper = list => list.filterNot(item => item === id);
+      state = state.updateIn([timeline, 'items'], helper).updateIn([timeline, 'pendingItems'], helper);
+    }
   });
 
   // Remove reblogs of deleted status
@@ -109,11 +121,10 @@ const filterTimelines = (state, relationship, statuses) => {
   return state;
 };
 
-const filterTimeline = (timeline, state, relationship, statuses) =>
-  state.updateIn([timeline, 'items'], ImmutableList(), list =>
-    list.filterNot(statusId =>
-      statuses.getIn([statusId, 'account']) === relationship.id
-    ));
+const filterTimeline = (timeline, state, relationship, statuses) => {
+  const helper = list => list.filterNot(statusId => statuses.getIn([statusId, 'account']) === relationship.id);
+  return state.updateIn([timeline, 'items'], ImmutableList(), helper).updateIn([timeline, 'pendingItems'], ImmutableList(), helper);
+};
 
 const updateTop = (state, timeline, top) => {
   return state.update(timeline, initialTimeline, map => map.withMutations(mMap => {
@@ -124,14 +135,17 @@ const updateTop = (state, timeline, top) => {
 
 export default function timelines(state = initialState, action) {
   switch(action.type) {
+  case TIMELINE_LOAD_PENDING:
+    return state.update(action.timeline, initialTimeline, map =>
+      map.update('items', list => map.get('pendingItems').concat(list.take(40))).set('pendingItems', ImmutableList()).set('unread', 0));
   case TIMELINE_EXPAND_REQUEST:
     return state.update(action.timeline, initialTimeline, map => map.set('isLoading', true));
   case TIMELINE_EXPAND_FAIL:
     return state.update(action.timeline, initialTimeline, map => map.set('isLoading', false));
   case TIMELINE_EXPAND_SUCCESS:
-    return expandNormalizedTimeline(state, action.timeline, fromJS(action.statuses), action.next, action.partial, action.isLoadingRecent);
+    return expandNormalizedTimeline(state, action.timeline, fromJS(action.statuses), action.next, action.partial, action.isLoadingRecent, action.usePendingItems);
   case TIMELINE_UPDATE:
-    return updateTimeline(state, action.timeline, fromJS(action.status));
+    return updateTimeline(state, action.timeline, fromJS(action.status), action.usePendingItems);
   case TIMELINE_DELETE:
     return deleteStatus(state, action.id, action.accountId, action.references, action.reblogOf);
   case TIMELINE_CLEAR:
@@ -149,7 +163,7 @@ export default function timelines(state = initialState, action) {
     return state.update(
       action.timeline,
       initialTimeline,
-      map => map.set('online', false).update('items', items => items.first() ? items.unshift(null) : items)
+      map => map.set('online', false).update(action.usePendingItems ? 'pendingItems' : 'items', items => items.first() ? items.unshift(null) : items)
     );
   default:
     return state;
diff --git a/app/lib/user_settings_decorator.rb b/app/lib/user_settings_decorator.rb
index aaf95cc19..9ae9986c2 100644
--- a/app/lib/user_settings_decorator.rb
+++ b/app/lib/user_settings_decorator.rb
@@ -35,6 +35,7 @@ class UserSettingsDecorator
     user.settings['show_application']    = show_application_preference if change?('setting_show_application')
     user.settings['advanced_layout']     = advanced_layout_preference if change?('setting_advanced_layout')
     user.settings['use_blurhash']        = use_blurhash_preference if change?('setting_use_blurhash')
+    user.settings['use_pending_items']   = use_pending_items_preference if change?('setting_use_pending_items')
   end
 
   def merged_notification_emails
@@ -117,6 +118,10 @@ class UserSettingsDecorator
     boolean_cast_setting 'setting_use_blurhash'
   end
 
+  def use_pending_items_preference
+    boolean_cast_setting 'setting_use_pending_items'
+  end
+
   def boolean_cast_setting(key)
     ActiveModel::Type::Boolean.new.cast(settings[key])
   end
diff --git a/app/models/user.rb b/app/models/user.rb
index 3a4b415dd..31c99630c 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -106,7 +106,7 @@ class User < ApplicationRecord
   delegate :auto_play_gif, :default_sensitive, :unfollow_modal, :boost_modal, :delete_modal,
            :reduce_motion, :system_font_ui, :noindex, :theme, :display_media, :hide_network,
            :expand_spoilers, :default_language, :aggregate_reblogs, :show_application,
-           :advanced_layout, :use_blurhash, to: :settings, prefix: :setting, allow_nil: false
+           :advanced_layout, :use_blurhash, :use_pending_items, to: :settings, prefix: :setting, allow_nil: false
 
   attr_reader :invite_code
   attr_writer :external
diff --git a/app/serializers/initial_state_serializer.rb b/app/serializers/initial_state_serializer.rb
index 54f99d570..7e5d3eda9 100644
--- a/app/serializers/initial_state_serializer.rb
+++ b/app/serializers/initial_state_serializer.rb
@@ -23,17 +23,18 @@ class InitialStateSerializer < ActiveModel::Serializer
     }
 
     if object.current_account
-      store[:me]              = object.current_account.id.to_s
-      store[:unfollow_modal]  = object.current_account.user.setting_unfollow_modal
-      store[:boost_modal]     = object.current_account.user.setting_boost_modal
-      store[:delete_modal]    = object.current_account.user.setting_delete_modal
-      store[:auto_play_gif]   = object.current_account.user.setting_auto_play_gif
-      store[:display_media]   = object.current_account.user.setting_display_media
-      store[:expand_spoilers] = object.current_account.user.setting_expand_spoilers
-      store[:reduce_motion]   = object.current_account.user.setting_reduce_motion
-      store[:advanced_layout] = object.current_account.user.setting_advanced_layout
-      store[:use_blurhash]    = object.current_account.user.setting_use_blurhash
-      store[:is_staff]        = object.current_account.user.staff?
+      store[:me]                = object.current_account.id.to_s
+      store[:unfollow_modal]    = object.current_account.user.setting_unfollow_modal
+      store[:boost_modal]       = object.current_account.user.setting_boost_modal
+      store[:delete_modal]      = object.current_account.user.setting_delete_modal
+      store[:auto_play_gif]     = object.current_account.user.setting_auto_play_gif
+      store[:display_media]     = object.current_account.user.setting_display_media
+      store[:expand_spoilers]   = object.current_account.user.setting_expand_spoilers
+      store[:reduce_motion]     = object.current_account.user.setting_reduce_motion
+      store[:advanced_layout]   = object.current_account.user.setting_advanced_layout
+      store[:use_blurhash]      = object.current_account.user.setting_use_blurhash
+      store[:use_pending_items] = object.current_account.user.setting_use_pending_items
+      store[:is_staff]          = object.current_account.user.staff?
     end
 
     store
diff --git a/app/views/settings/preferences/appearance/show.html.haml b/app/views/settings/preferences/appearance/show.html.haml
index c13882801..e279a61c4 100644
--- a/app/views/settings/preferences/appearance/show.html.haml
+++ b/app/views/settings/preferences/appearance/show.html.haml
@@ -18,6 +18,9 @@
   %h4= t 'appearance.animations_and_accessibility'
 
   .fields-group
+    = f.input :setting_use_pending_items, as: :boolean, wrapper: :with_label
+
+  .fields-group
     = f.input :setting_auto_play_gif, as: :boolean, wrapper: :with_label, recommended: true
     = f.input :setting_reduce_motion, as: :boolean, wrapper: :with_label
     = f.input :setting_system_font_ui, as: :boolean, wrapper: :with_label
diff --git a/config/locales/simple_form.en.yml b/config/locales/simple_form.en.yml
index 75cbec9de..12a7ec2b3 100644
--- a/config/locales/simple_form.en.yml
+++ b/config/locales/simple_form.en.yml
@@ -35,6 +35,7 @@ en:
         setting_noindex: Affects your public profile and status pages
         setting_show_application: The application you use to toot will be displayed in the detailed view of your toots
         setting_use_blurhash: Gradients are based on the colors of the hidden visuals but obfuscate any details
+        setting_use_pending_items: Hide timeline updates behind a click instead of automatically scrolling the feed
         username: Your username will be unique on %{domain}
         whole_word: When the keyword or phrase is alphanumeric only, it will only be applied if it matches the whole word
       featured_tag:
@@ -111,6 +112,7 @@ en:
         setting_theme: Site theme
         setting_unfollow_modal: Show confirmation dialog before unfollowing someone
         setting_use_blurhash: Show colorful gradients for hidden media
+        setting_use_pending_items: Slow mode
         severity: Severity
         type: Import type
         username: Username
diff --git a/config/settings.yml b/config/settings.yml
index ad71b6008..75cb2dc85 100644
--- a/config/settings.yml
+++ b/config/settings.yml
@@ -33,6 +33,7 @@ defaults: &defaults
   aggregate_reblogs: true
   advanced_layout: false
   use_blurhash: true
+  use_pending_items: false
   notification_emails:
     follow: false
     reblog: false