perf(core): parallelize user quota and experiments fetching in refreshAuth (#21648)

packages/core/src/config/config.ts

@@ -779,7 +779,7 @@ export class Config implements McpContext, AgentLoopContext {
     | undefined;
   private disabledHooks: string[];
   private experiments: Experiments | undefined;
-  private experimentsPromise: Promise<void> | undefined;
+  private experimentsPromise: Promise<Experiments | undefined> | undefined;
   private hookSystem?: HookSystem;
   private readonly onModelChange: ((model: string) => void) | undefined;
   private readonly onReload:
@@ -1269,18 +1269,22 @@ export class Config implements McpContext, AgentLoopContext {
     this.baseLlmClient = new BaseLlmClient(this.contentGenerator, this);
 
     const codeAssistServer = getCodeAssistServer(this);
-    if (codeAssistServer?.projectId) {
-      await this.refreshUserQuota();
-    }
+    const quotaPromise = codeAssistServer?.projectId
+      ? this.refreshUserQuota()
+      : Promise.resolve();
 
     this.experimentsPromise = getExperiments(codeAssistServer)
       .then((experiments) => {
         this.setExperiments(experiments);
+        return experiments;
       })
       .catch((e) => {
         debugLogger.error('Failed to fetch experiments', e);
+        return undefined;
       });
 
+    await quotaPromise;
+
     const authType = this.contentGeneratorConfig.authType;
     if (
       authType === AuthType.USE_GEMINI ||
@@ -1296,10 +1300,10 @@ export class Config implements McpContext, AgentLoopContext {
     }
 
     // Fetch admin controls
-    await this.ensureExperimentsLoaded();
+    const experiments = await this.experimentsPromise;
     const adminControlsEnabled =
-      this.experiments?.flags[ExperimentFlags.ENABLE_ADMIN_CONTROLS]
-        ?.boolValue ?? false;
+      experiments?.flags[ExperimentFlags.ENABLE_ADMIN_CONTROLS]?.boolValue ??
+      false;
     const adminControls = await fetchAdminControls(
       codeAssistServer,
       this.getRemoteAdminSettings(),