Odd performance issue (Raspberry Pi 5)

Description

When opening content first after opening RetroArch (Apt version on Ubuntu 23.10 on Raspberry Pi 5), performance will be worse than when closing and reopening the content. Specifically, in my case, opening Beetle PSX first will cause severe lag (Doesn't seem to be CPU, audio, shader, or filter related as the same issue happens when all are disabled, and CPU core load doesn't go above 50%) whereas opening any content (even if the core is different, tested with Beetle PSX, FCEUmm and bsnes-mercury Performance) and closing it before opening Beetle PSX will result in no lag. Logs don't seem to show any difference. This seems to only happen in Beetle PSX so it might also be a Beetle issue.
Please note that restarting the content does not fix the issue, only closing and reopening it does.

Expected behavior

Performance should not change significantly between loads.

Actual behavior

First load performance will be worse.

Steps to reproduce the bug

1. Open RetroArch
2. Load content
3. Notice it has performance issues
4. Close content
5. Reopen the content
6. Performance issues are gone

Version/Commit

• RetroArch: 1.17.0
• Git version: r202402040217~fb63c79f32
• Core version: Beetle PSX (0.9.44.10.9.44.1+r202402021331~fb579de8)

Environment information

• OS: Ubuntu 23.10
• Compiler: N/A (apt)

Reproduce the reported sequence on a Raspberry Pi 5 with Ubuntu 23.10: load Beetle PSX first, close it, then load it again, and compare performance and available logs. Check whether the behavior is specific to Beetle PSX or RetroArch's first content load; done means identifying and fixing the first-load performance difference without regressing other cores.