perf(app): cut idle renderer CPU and unbounded memory growth (#1724)

fluxer_app/src/features/user/state/Users.ts

@@ -55,6 +55,7 @@ function isPublicOnlyCurrentUserPayload(user: WireUser): boolean {
 
 class Users {
 	users: Record<string, User> = {};
+	userCount = 0;
 
 	constructor() {
 		makeAutoObservable(this, {}, {autoBind: true});
@@ -98,6 +99,7 @@ class Users {
 		this.users = {
 			[currentUser.id]: userRecord,
 		};
+		this.userCount = 1;
 		if (!userRecord.isClaimed()) {
 			setTimeout(async () => {
 				openClaimAccountModal();
@@ -121,7 +123,18 @@ class Users {
 		) {
 			return;
 		}
-		this.users[user.id] = existingUser ? existingUser.withUpdates(user, options) : new User(user);
+		this.storeUser(existingUser, existingUser ? existingUser.withUpdates(user, options) : new User(user));
+	}
+
+	private storeUser(existingUser: User | undefined, nextUser: User): void {
+		if (existingUser) {
+			if (existingUser.equals(nextUser)) {
+				return;
+			}
+		} else {
+			this.userCount += 1;
+		}
+		this.users[nextUser.id] = nextUser;
 	}
 
 	cacheUsers(
@@ -137,14 +150,14 @@ class Users {
 				if (user.id === this.currentUserId && existingUser && isPublicOnlyCurrentUserPayload(user)) {
 					continue;
 				}
-				this.users[user.id] = existingUser ? existingUser.withUpdates(user) : new User(user);
+				this.storeUser(existingUser, existingUser ? existingUser.withUpdates(user) : new User(user));
 			}
 		});
 	}
 
 	subscribe(callback: () => void): () => void {
 		return reaction(
-			() => Object.keys(this.users).length,
+			() => this.userCount,
 			() => callback(),
 			{fireImmediately: true},
 		);