Did you check the temperature of the cpu and gpu? It might be a overheating problem that causes the fps drops.

I prefer AUR packages, but it depends on how many AUR dependencies it uses and how well maintained and used by others it is, I rely mainly on the official repo and try to use AUR and others in a complementary way, I also don’t run any AppImages, just the ones from open-source applications and that I trust minimally.

Why do you consider AppImages as last resort?

I can understand that in a distro the main repo need to be prioritized to avoid bloat of repetitive dependencies that could happen with a lot of AppImages.

I can’t understand why so many people are opposed to it as an supportive role from a practical and complementary perspective.

Canonical sure know how to name them.