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

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

Reproduce on Windows 11 with WASAPI, Sync to Exact Content Framerate, FreeSync or GSYNC, and the default pause hotkey; compare GPU usage, framepacing, and audio before and after pausing. Check the video and audio behavior with Vulkan and D3D11, and consider the issue done when unpausing no longer causes the reported persistent GPU and audio impact.