Video performance issues in web browser source in 31

Operating System Info

Windows 11

Other OS

No response

OBS Studio Version

31.0.0

OBS Studio Version (Other)

No response

OBS Studio Log URL

https://obsproject.com/logs/9nLLWWxZaLTtIVAE

OBS Studio Crash Log URL

No response

Expected Behavior

We've been doing some testing of the browser source/docks CEF updates to version 127 as part of OBS Studio 31 and we've noticed a huge performance hit in the way the web browser source renders multiple videos and iframes on the page that's displayed within the web browser source. Previously on 30.2, our Overlay could easily render 15+ videos all embedded within iframes without skipping a beat.

Current Behavior

However on 31, doing any more than a couple at a time can easily freeze all the videos that are being rendered and keep them hanging on the screen itself. Doing some remote debugging on both versions, I don't see any errors cropping up within the console and nothing looks awry with any of the profiling I was doing, but it's a very obvious performance difference between the versions. We've gotten multiple reports from users who have encountered this only since upgrading to any version of 31, but don't encounter it when downgrading back to 30.

Steps to Reproduce

1. Create a web browser source
2. Link it to a simple HTML file that repeatedly creates iframes with a single tag inside of it
3. Save the web browser source and let it begin running

Anything else we should know?

Comparison videos included below to show the difference. First one is from 30, second one is from 31:

https://github.com/user-attachments/assets/926ab780-3b30-46bb-823c-68b4223b08bb

https://github.com/user-attachments/assets/84acc22d-2b6a-48d9-abb3-2096019c8f9e

Start with the OBS browser source rendering path and the CEF 127 update involved in OBS Studio 31. Reproduce the issue with an HTML file that creates multiple iframes containing video elements, then compare behavior against OBS Studio 30.2 using the provided log and comparison videos. Done means multiple videos render without freezing or the regression is narrowed to a specific component.