I upgraded to Big Sur on Monday and then updated Zoom to the latest version. The problem is when using a virtual background, the aomhost process uses more than 90% of my CPU. I have a powerful macbook pro that I purchased this summer. According to the help center at Zoom: "As of now Big Sur is not yet compatible with the Zoom app. However, may I suggest to downgrade either your Zoom App or the Os system that you have."
Any other suggestions?