PPSSPP options explained

[[Unknown]]

JIT is only applied on reset. You're probably right about 2x res.

Fastmem is, to a degree, only applied on reset. Specifically, sections of code that have been jitted will retain the old setting, but new code will get the new setting.

As current, if you want fastmem changes to apply immediately to everything, you'll need to savestate after changing the setting. Saving state clears the jit cache.

-[Unknown]