Fix slow import when window is unfocused

editor/editor_file_system.cpp

@@ -1988,7 +1988,7 @@ void EditorFileSystem::_update_scene_groups() {
 		}
 
 		if (ep) {
-			ep->step(efd->files[index]->file, step_count++);
+			ep->step(efd->files[index]->file, step_count++, false);
 		}
 	}
 
@@ -2706,6 +2706,16 @@ void EditorFileSystem::reimport_files(const Vector<String> &p_files) {
 
 	EditorProgress *ep = memnew(EditorProgress("reimport", TTR("(Re)Importing Assets"), p_files.size()));
 
+	// The method reimport_files runs on the main thread, and if VSync is enabled
+	// or Update Continuously is disabled, Main::Iteration takes longer each frame.
+	// Each EditorProgress::step can trigger a redraw, and when there are many files to import,
+	// this could lead to a slow import process, especially when the editor is unfocused.
+	// Temporarily disabling VSync and low_processor_usage_mode while reimporting fixes this.
+	const bool old_low_processor_usage_mode = OS::get_singleton()->is_in_low_processor_usage_mode();
+	const DisplayServer::VSyncMode old_vsync_mode = DisplayServer::get_singleton()->window_get_vsync_mode(DisplayServer::MAIN_WINDOW_ID);
+	OS::get_singleton()->set_low_processor_usage_mode(false);
+	DisplayServer::get_singleton()->window_set_vsync_mode(DisplayServer::VSyncMode::VSYNC_DISABLED);
+
 	Vector<ImportFile> reimport_files;
 
 	HashSet<String> groups_to_reimport;
@@ -2836,13 +2846,19 @@ void EditorFileSystem::reimport_files(const Vector<String> &p_files) {
 			}
 		}
 	}
+	ep->step(TTR("Finalizing Asset Import..."), p_files.size());
 
 	ResourceUID::get_singleton()->update_cache(); // After reimporting, update the cache.
 	_save_filesystem_cache();
 
 	memdelete_notnull(ep);
 
 	_process_update_pending();
+
+	// Revert to previous values to restore editor settings for VSync and Update Continuously.
+	OS::get_singleton()->set_low_processor_usage_mode(old_low_processor_usage_mode);
+	DisplayServer::get_singleton()->window_set_vsync_mode(old_vsync_mode);
+
 	importing = false;
 
 	ep = memnew(EditorProgress("reimport", TTR("(Re)Importing Assets"), p_files.size()));

editor/progress_dialog.cpp

@@ -202,22 +202,21 @@ void ProgressDialog::add_task(const String &p_task, const String &p_label, int p
 bool ProgressDialog::task_step(const String &p_task, const String &p_state, int p_step, bool p_force_redraw) {
 	ERR_FAIL_COND_V(!tasks.has(p_task), canceled);
 
+	Task &t = tasks[p_task];
 	if (!p_force_redraw) {
 		uint64_t tus = OS::get_singleton()->get_ticks_usec();
-		if (tus - last_progress_tick < 200000) { //200ms
+		if (tus - t.last_progress_tick < 200000) { //200ms
 			return canceled;
 		}
 	}
-
-	Task &t = tasks[p_task];
 	if (p_step < 0) {
 		t.progress->set_value(t.progress->get_value() + 1);
 	} else {
 		t.progress->set_value(p_step);
 	}
 
 	t.state->set_text(p_state);
-	last_progress_tick = OS::get_singleton()->get_ticks_usec();
+	t.last_progress_tick = OS::get_singleton()->get_ticks_usec();
 	_update_ui();
 
 	return canceled;
@@ -252,7 +251,6 @@ ProgressDialog::ProgressDialog() {
 	main->set_anchors_and_offsets_preset(Control::PRESET_FULL_RECT);
 	set_exclusive(true);
 	set_flag(Window::FLAG_POPUP, false);
-	last_progress_tick = 0;
 	singleton = this;
 	cancel_hb = memnew(HBoxContainer);
 	main->add_child(cancel_hb);

editor/progress_dialog.h

@@ -71,13 +71,13 @@ class ProgressDialog : public PopupPanel {
 		VBoxContainer *vb = nullptr;
 		ProgressBar *progress = nullptr;
 		Label *state = nullptr;
+		uint64_t last_progress_tick = 0;
 	};
 	HBoxContainer *cancel_hb = nullptr;
 	Button *cancel = nullptr;
 
 	HashMap<String, Task> tasks;
 	VBoxContainer *main = nullptr;
-	uint64_t last_progress_tick;
 
 	LocalVector<Window *> host_windows;