I had the same issue as you but I'm not on the controller so that was not the issue for me. I uninstalled and reinstalled plutonium as well and when I came back to play multiplayer or zombies it would be smooth and then I end up with 10 FPS. Now I'm not sure exactly what I did to fix it but what I did was I moved the pluto full game file to a new folder deleted the old one and changed the directory, I also rechecked windows updates and there were a few I was missing. I highly doubt this is a huge problem anymore but I felt the need to let others know there's a fix to this game-breaking issue.
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DMedo
@DMedo