I don't know what happened but the game seems to perform like normal for me now. Except, after about 2 games, in the middle of the 3rd game the FPS drops massively. Some sort of memory leak. What's frustrating is that the only solution I found was to just restart the game. But even if I ask for a pause, restarting the game means pre-loading again. Which takes time. By the time it finishes, the game has already continued. Even if the enemy was kind enough to wait, they never wait that long.