Enabling "Sync to Exact Content Framerate" causes a GPU usage % drop when using RetroArch's Pause (default hotkey "p") and WASAPI driver

[notNSANE]

Is there an existing issue for this?

• This is a bug in RetroArch frontend
• I have searched the existing issues

Description

After you pause/unpause using RetroArch's pause (which is also triggered by alt-tabbing), GPU usage gets a permanent hit, causing audio crackles and slightly more unstable framepacing.

I spent around 2 hours tweaking and testing every single option, one by one, related to audio and vsync and this has been the culprit. At first I thought it was the audio driver, because switching from WASAPI to any other fixed the issue, but WASAPI shouldn't lower GPU usage after a pause on itself.

So, to get this, you need WASAPI audio driver, FreeSync/GSYNC option enabled, and then pause/unpause with RetroArch (not the game's own pause).

You also need a decent tool to observe framepacing, Steam has a great one now.

Expected behavior

GPU usage remains normal after unpausing/resuming.

Steps to reproduce the bug

1. Use a clean RetroArch install
2. Enable Sync to Exact Content Framerate in Video settings
3. Save settings and restart RetroArch
4. Load a game
5. Enable your framepacing tool (Steam / MSI Afterburner, etc.)
6. In-game, and when there's music, press the letter "p" on the keyboard twice
7. Observe the graphs and listen to the music

Version/Commit

1.21.0 (Steam)

Bisect Results

No response

Present in the nightly version

I don't know

Platform & operating system

Windows 11 25H2

Affected Cores

No response

Environment information

• As mentioned, this issue only happens with WASAPI
• Issue happens with vulkan and d3d11, albeit slightly differently
• Tested with an AMD 6650 XT, Adrenaline's RetroArch settings are defaults
• Issue is easier to be heard when using a very heavy Mega Bezel (Guest's is a good one)
• Parameters tested that werent' the cause of the issue: other video drivers, vsync swap, adaptive vsync, exclusive and windowed fullscreen, d3d12/11, wasapi sinc/cc/nearest, wasapi quality

Relevant log output

[notNSANE]

related issues: #18246 #15920