I've only ever played on my Lenovo P12 Pro tablet and I've always had perfect performance. Since the latest update (the one announcing the tie in with Attack on Titan) there has been noticeable stuttering, so much so that it makes it difficult to play. I'm currently running version 5.3.6. Nothing has changed on my tablet, not even the installed apps.
#Performance decrease since latest update
sharp barn
stable ocean
The update hasn't happened yet...
5.3.6 update is from early April.
sharp barn
Huh. I just thought noticed a decrease in performance exactly when the title screen got it's scary makeover and the AoT announcement. I must be wrong I guess.
flat harnessBOT
it's an easter egg 
stable ocean
No idea how long that's been in the game - years, at least
But yeah, it's just a one-time thing
If your device is cool now, I guess it's all good
sharp barn
Yeah, I've seen a couple versions of the title screen now, but that doesn't stop the stuttering during gameplay. I figured adding the announcement banner and the extra title screens would have involved a small update, but I must not understand how this works. I don't mean to poke at a game that I really enjoy. It just seemed like it went from very, very smooth to a whole lot less smooth right around the time of adding the announcement. I may be wrong, but my wife, who trades off playing this with me while we're hanging out, noticed it first. She's not even a "gamer," so I thought that might mean something. I very well could be wrong though. We'll see what the next patch/update is like.
The device is definitely not cool now. Still very stuttery. And I'm pretty sure this tablet (Lenovo P12 Pro) should be plenty powerful enough to run this. But idk, I'm no expert.