I am having also having this issue, particularly, with the Messages app. I get the pinwheel and/or terrible lag whenever I try to type a message in the app. This is my favorite feature and it is totally unusable! Wish everybody would just use WhatsApp now. Had the same problem with Catalina and hoped that Big Sur would correct this issue. Tried everything suggested. No joy.
MacBook Air (Retina, 13-inch, 2020)
1 .1 GHz Dual-Core Intel Core i3
8 GB 3733 MHz LPDDR4X
Intel Iris Plus Graphics 1536 MB