some games of TFT FPS so slow it's unplayable

Not all the games are like this for me. But every now and then this happens. I can't center the screen on the little legend and the game starts without me seeing the first carousel. Those are good first indicators. Also in the loading screen it never finishes to 100% maybe just 12%. That's how I know it'll be broken. The FPS will shoot up and down between 60 and 00. It's so slow I can't even buy champions in the store, etc. It's unplayable in this state. Exiting the game and reconnecting does nothing. Restarting my PC does nothing. Doing a "full repair" does nothing. I finally was able to surrender and start a new game to see if it is still like this. It kept doing the same thing.

I played all afternoon earlier with no problem, but suddenly there are issues again and I don't see any way to solve it. Help would be appreciated. Oh also the bug report button doesn't seem to be working...