Fix new performance regressions (short delay_usec)

My Mac was using 20% cpu again, which was related to the Javascript
Export plugin.

I had however no export templates setup in the project so this is more
of a stopgap fix.

platform/javascript/export/export_plugin.cpp

@@ -645,7 +645,7 @@ Ref<Texture2D> EditorExportPlatformJavaScript::get_run_icon() const {
 void EditorExportPlatformJavaScript::_server_thread_poll(void *data) {
 	EditorExportPlatformJavaScript *ej = (EditorExportPlatformJavaScript *)data;
 	while (!ej->server_quit) {
-		OS::get_singleton()->delay_usec(1000);
+		OS::get_singleton()->delay_usec(6900);
 		{
 			MutexLock lock(ej->server_lock);
 			ej->server->poll();