fix: perf (#3906)

lib/Server.js

@@ -36,13 +36,13 @@ class Server {
     this.webSocketProxies = [];
     this.sockets = [];
     this.compiler = compiler;
+    this.currentHash = null;
   }
 
   static get DEFAULT_STATS() {
     return {
       all: false,
       hash: true,
-      assets: true,
       warnings: true,
       errors: true,
       errorDetails: false,
@@ -1970,13 +1970,13 @@ class Server {
 
   // eslint-disable-next-line class-methods-use-this
   sendMessage(clients, type, data) {
-    clients.forEach((client) => {
+    for (const client of clients) {
       // `sockjs` uses `1` to indicate client is ready to accept data
       // `ws` uses `WebSocket.OPEN`, but it is mean `1` too
       if (client.readyState === 1) {
         client.send(JSON.stringify({ type, data }));
       }
-    });
+    }
   }
 
   serveMagicHtml(req, res, next) {
@@ -2011,15 +2011,15 @@ class Server {
       stats &&
       (!stats.errors || stats.errors.length === 0) &&
       (!stats.warnings || stats.warnings.length === 0) &&
-      stats.assets &&
-      stats.assets.every((asset) => !asset.emitted);
+      this.currentHash === stats.hash;
 
     if (shouldEmit) {
       this.sendMessage(clients, "still-ok");
 
       return;
     }
 
+    this.currentHash = stats.hash;
     this.sendMessage(clients, "hash", stats.hash);
 
     if (stats.errors.length > 0 || stats.warnings.length > 0) {