Merge pull request #103773 from Calinou/windows-low-processor-mode-sleep-cpu

Use more efficient sleep approach on Windows when low-processor mode is enabled

platform/windows/os_windows.cpp

@@ -2340,18 +2340,26 @@ void OS_Windows::add_frame_delay(bool p_can_draw) {
 		target_ticks += dynamic_delay;
 		uint64_t current_ticks = get_ticks_usec();
 
-		if (target_ticks > current_ticks + delay_resolution) {
-			uint64_t delay_time = target_ticks - current_ticks - delay_resolution;
-			// Make sure we always sleep for a multiple of delay_resolution to avoid overshooting.
-			// Refer to: https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-sleep#remarks
-			delay_time = (delay_time / delay_resolution) * delay_resolution;
-			if (delay_time > 0) {
-				delay_usec(delay_time);
+		if (!is_in_low_processor_usage_mode()) {
+			if (target_ticks > current_ticks + delay_resolution) {
+				uint64_t delay_time = target_ticks - current_ticks - delay_resolution;
+				// Make sure we always sleep for a multiple of delay_resolution to avoid overshooting.
+				// Refer to: https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-sleep#remarks
+				delay_time = (delay_time / delay_resolution) * delay_resolution;
+				if (delay_time > 0) {
+					delay_usec(delay_time);
+				}
+			}
+			// Busy wait for the remainder of time.
+			while (get_ticks_usec() < target_ticks) {
+				YieldProcessor();
+			}
+		} else {
+			// Use a more relaxed approach for low processor usage mode.
+			// This has worse frame pacing but is more power efficient.
+			if (current_ticks < target_ticks) {
+				delay_usec(target_ticks - current_ticks);
 			}
-		}
-		// Busy wait for the remainder of time.
-		while (get_ticks_usec() < target_ticks) {
-			YieldProcessor();
 		}
 
 		current_ticks = get_ticks_usec();