Hey, same frustration here. Yesterday I've bought an iMac 4K, 21.5-inch, 2019, with Big Sur. I've bought it because I thought it's a good idea to work on Mac to complete my maser thesis.. I made good experience with iPad Pro and thought I would experience the same productivity with an iMac But Big Sur is Big Fail - it takes 10 to 20 seconds to just open small Apps like Notes.. The 1TB HDD ist non-stop(!) working. Why is apple not immediately solving this Big Problem???