Revert "change low cpu delay to 1 usec, should make editor smoother and not really use"

This reverts commit ca194033061b4b29fe00d8e9bddf2f0478b3c3f0.

See discussion in https://github.com/godotengine/godot/commit/ca194033061b4b29fe00d8e9bddf2f0478b3c3f0#commitcomment-25715906
It also did not fix the issue it claimed to fix.

main/main.cpp

@@ -1766,8 +1766,7 @@ bool Main::iteration() {
 		return exit;
 
 	if (OS::get_singleton()->is_in_low_processor_usage_mode() || !OS::get_singleton()->can_draw())
-		//OS::get_singleton()->delay_usec(16600); //apply some delay to force idle time (results in about 60 FPS max)
-		OS::get_singleton()->delay_usec(1000); //apply some delay to force idle time (results in about 60 FPS max)
+		OS::get_singleton()->delay_usec(16600); //apply some delay to force idle time (results in about 60 FPS max)
 	else {
 		uint32_t frame_delay = Engine::get_singleton()->get_frame_delay();
 		if (frame_delay)