I spoof on the Galaxy Tab S2 and I think the game runs terrible on it. Lots of frame drops. It crashes a lot randomly. The visual quality of the game isn't great either. In raids you can't see the display message when the pokemon is going to use a move on you. When you're attempting to catch a raid pokemon you can not see the amount of premier balls you have as its off the screen.
I started playing the game on an iPhone and I've been spoiled by the luxury it provides. The iPhones smoothness and stability is on a whole other level.
However, throwing pokeballs on the tablet is super easy compared to a phone. Never have the problem where the pokemon is too far for the ball to reach.