Avast version 121230-1 is slowing down gaming even if game folders are on the exclusions list. It didn’t do this before the recent update. I will not recommend anymore if this can’t be resolved.
I highly doubt it’s avast!. In fact i’ve never had any AV slowing down games. I suggest you check which process is consuming the most CPU while you’re playing games (use process explorer or other more advanced process manager to check that).