I’m not sure when this started as the last version I’ve played before 2.1.2 was the one right before the trials update but it seems performance in battles is really bad on my Huawei T1 7.0 Android 4.2. The game stutters and freezes in short bursts when there are fading effects (both for text and images) and attack animations. It causes battles to take significantly than they should. High performance mode doesn’t seem to change anything at all.
As I said, this didn’t happen before the trials update.
EDIT: It seems also that enemies take a lot longer to start their turns each move.