Fix sidebar subs inefficiencies

- `filteredSubscriptions` was running the filter code whether or not it actually required filtering, because the `!subscriptionFilter` logic is placed in the predicate. While it is a clean one-liner, it is slow when the subs list is huge.
    - While at it, moved the code into `getSubscriptionSection` to isolate things.

- The sidebar was resolving the entire subs list, which is super slow for a list of 500+. Since we now have a "Manage Subscriptions" page, just batch-resolve the N visible subs.
    - TODO: the code should probably be moved from 'app' to 'sideNavigate'.

ui/component/app/view.jsx

@@ -23,6 +23,7 @@ import usePersistedState from 'effects/use-persisted-state';
 import useConnectionStatus from 'effects/use-connection-status';
 import Spinner from 'component/spinner';
 import LANGUAGES from 'constants/languages';
+import { SIDEBAR_SUBS_DISPLAYED } from 'constants/subscriptions';
 import YoutubeWelcome from 'web/component/youtubeReferralWelcome';
 import {
   useDegradedPerformance,
@@ -477,7 +478,7 @@ function App(props: Props) {
   useLayoutEffect(() => {
     if (sidebarOpen && isPersonalized && subscriptions && !resolvedSubscriptions) {
       setResolvedSubscriptions(true);
-      resolveUris(subscriptions.map((sub) => sub.uri));
+      resolveUris(subscriptions.slice(0, SIDEBAR_SUBS_DISPLAYED).map((sub) => sub.uri));
     }
   }, [sidebarOpen, isPersonalized, resolvedSubscriptions, subscriptions, resolveUris, setResolvedSubscriptions]);
 

ui/component/sideNavigation/view.jsx

@@ -3,6 +3,7 @@ import type { Node } from 'react';
 import * as PAGES from 'constants/pages';
 import * as ICONS from 'constants/icons';
 import * as KEYCODES from 'constants/keycodes';
+import { SIDEBAR_SUBS_DISPLAYED } from 'constants/subscriptions';
 import React, { useEffect } from 'react';
 import Button from 'component/button';
 import ClaimPreviewTitle from 'component/claimPreviewTitle';
@@ -16,7 +17,6 @@ import { useIsMobile, useIsLargeScreen, isTouch } from 'effects/use-screensize';
 import { GetLinksData } from 'util/buildHomepage';
 import { DOMAIN, ENABLE_UI_NOTIFICATIONS, ENABLE_NO_SOURCE_CLAIMS, CHANNEL_STAKED_LEVEL_LIVESTREAM } from 'config';
 
-const FOLLOWED_ITEM_INITIAL_LIMIT = 10;
 const touch = isTouch();
 
 type SideNavLink = {
@@ -265,23 +265,13 @@ function SideNavigation(props: Props) {
   const showPushMenu = sidebarOpen && !menuCanCloseCompletely;
   const showOverlay = isAbsolute && sidebarOpen;
 
-  const showSubscriptionSection = shouldRenderLargeMenu && isPersonalized && subscriptions && subscriptions.length > 0;
   const showTagSection = sidebarOpen && isPersonalized && followedTags && followedTags.length;
 
   const [subscriptionFilter, setSubscriptionFilter] = React.useState('');
 
-  const filteredSubscriptions = subscriptions.filter(
-    (sub) => !subscriptionFilter || sub.channelName.toLowerCase().includes(subscriptionFilter.toLowerCase())
-  );
-
-  let displayedSubscriptions = filteredSubscriptions;
-  if (showSubscriptionSection && !subscriptionFilter && subscriptions.length > FOLLOWED_ITEM_INITIAL_LIMIT) {
-    displayedSubscriptions = subscriptions.slice(0, FOLLOWED_ITEM_INITIAL_LIMIT);
-  }
-
   let displayedFollowedTags = followedTags;
-  if (showTagSection && followedTags.length > FOLLOWED_ITEM_INITIAL_LIMIT && !expandTags) {
+  if (showTagSection && followedTags.length > SIDEBAR_SUBS_DISPLAYED && !expandTags) {
-    displayedFollowedTags = followedTags.slice(0, FOLLOWED_ITEM_INITIAL_LIMIT);
+    displayedFollowedTags = followedTags.slice(0, SIDEBAR_SUBS_DISPLAYED);
   }
 
   function getLink(props: SideNavLink) {
@@ -312,11 +302,20 @@ function SideNavigation(props: Props) {
   }
 
   function getSubscriptionSection() {
-    if (showSubscriptionSection) {
+    const showSubsSection = shouldRenderLargeMenu && isPersonalized && subscriptions && subscriptions.length > 0;
+    if (showSubsSection) {
+      let displayedSubscriptions;
+      if (subscriptionFilter) {
+        const filter = subscriptionFilter.toLowerCase();
+        displayedSubscriptions = subscriptions.filter((sub) => sub.channelName.toLowerCase().includes(filter));
+      } else {
+        displayedSubscriptions = subscriptions.slice(0, SIDEBAR_SUBS_DISPLAYED);
+      }
+
       return (
         <>
           <ul className="navigation__secondary navigation-links">
-            {subscriptions.length > FOLLOWED_ITEM_INITIAL_LIMIT && (
+            {subscriptions.length > SIDEBAR_SUBS_DISPLAYED && (
               <li className="navigation-item">
                 <DebouncedInput icon={ICONS.SEARCH} placeholder={__('Filter')} onChange={setSubscriptionFilter} />
               </li>
@@ -356,7 +355,7 @@ function SideNavigation(props: Props) {
                 <Button navigate={`/$/discover?t=${name}`} label={`#${name}`} className="navigation-link" />
               </li>
             ))}
-            {followedTags.length > FOLLOWED_ITEM_INITIAL_LIMIT && (
+            {followedTags.length > SIDEBAR_SUBS_DISPLAYED && (
               <Button
                 key="showMore"
                 label={expandTags ? __('Show less') : __('Show more')}

ui/constants/subscriptions.js

@@ -10,3 +10,6 @@ export const NOTIFY_ONLY = 'NOTIFY_ONLY;';
 export const SUGGESTED_TOP_BID = 'top_bid';
 export const SUGGESTED_TOP_SUBSCRIBED = 'top_subscribed';
 export const SUGGESTED_FEATURED = 'featured';
+
+// Sidebar UI
+export const SIDEBAR_SUBS_DISPLAYED = 10;