tl;dr: You have to wait until August, when I have access to a 3DS again. Have basicly no hardware at all at my current location besides my Laptop.
Thanks for the feedback. When I have a 3DS again will try to find the reason for the bad performance. I already observed in January that the performance regressed a bit. I was e.g. unable to reach 60 FPS (which worked before).
Right, the audio does actually pitch: For SEs due to how they are handled (they are decoded once and kept in memory) compared to BGMs which are streamed (to clarify: BGMs are not pitched on old3ds). That SEs play all at once or cause BGM issues makes no sense either because BGM runs independend of SE (I think the problem is here that both BGM and SE (while decoding) read from the SD card at the same time and that's too much for the slow SD card interface of the 3DS)
BattleAnimations were already a problem on the Wii afaik, maybe we should really investigate whats wrong with them :o
This out of memory problem was also one thing we tried to solve but always when increasing the heap (the space in memory where stuff is allocated) it worked in Citra but crashed on hardware :/. We also have something else planned to reduce memory usage in general, but this isn't ready yet ^^.
Btw is the data abort when closing the CIA is gone? We had a double free in our code (deleted a texture twice).