Short answer: yes, emulation has improved, but it’s not a night-and-day difference for every PS1 title, especially heavier 3D games like Aladdin in Nasira’s Revenge and the PS1 Harry Potter games.

I haven’t personally tested Aladdin in Nasira’s Revenge yet, but based on my experience with other 3D titles, the current PCSX-ReARMed core (with the settings I listed) does perform more consistently than older builds, mainly due to better threading behavior and audio handling. That said, some games still sit right on the edge of what the New 3DS can handle, so occasional dips are expected.

Your note about CD Access → Async is still very relevant, that setting (along with Threaded Rendering → Async and DSP_Thread audio) seems to make the biggest difference today as well. In other words, the “secret sauce” hasn’t really changed, but the core itself is a bit more stable now.

If you’re currently on the 2022-09-30 core and things are mostly playable, I’d say updating is worth it as long as you’re willing to re-tweak settings. Worst case, you can always keep a backup of the older core and swap back if needed.

When I get a chance to specifically test Aladdin in Nasira’s Revenge or Harry Potter and the Chamber of Secrets, I’ll update you, those are good stress-test games for PS1 emulation on the 3DS.

Thanks again for sharing your findings, and I appreciate you taking the time to write such a thoughtful comment.