There are probably several ways, each with their own problems.
If you can find some input-events component you may try to remove it.
As I said before, maybe removing the colliders would help, even if it means finding another way to avoid the player not to fall.
There’s this thread which may help you:
Also, have you tried in standalone instead of within the editor?
Maybe there’s no performance problem in standalone, who knows, luck does happen sometimes.