My “kinda new to me” Pixel 4a (I know its EOL and not new) is the fastest phone I currently have.
I run GrapheneOS on it, based on Android 13 with latest updates.
But also it has a hardened Kernel and Malloc, which may be the problem here.
In comparison: A Nokia 7+ with unofficial LineageOS based off Android 13. And a Google Nexus 5 or so, with some very old Android 8 or so.
OpenCamera works perfectly well on both the non GrapheneOS phones? But on my pixel, it loads extremely slowly, like 10s at least. Its pretty unusable.
OpenCamera is a weird project, I can imagine this is a memory overflow or something, so the hardened Malloc is the problem.
OpenCamera only has a SourceForge repo which is very weird. Do you use it and have an idea why this is happening?
You could open an issue or contact the author:
https://sourceforge.net/p/opencamera/code/ci/master/tree/
https://opencamera.org.uk/index.html