Accidentally I noticed two things after the update to macOS 11 (Big Sur) that drove me nuts during the past year that I am using the 16" MacBook Pro and that now seem to be fixed: fan craziness and mouse dongle stupidity.
If you followed this blog you learned I had to make compromises with my setup, the cables, how the machine resides on my desk and with software I can use without having trouble.
The fan was my constant companion during the past year even when I didn't do much on this machine. Remember: I had serious thermal issues depending on the external monitors I used and even how I had the MacBook stand on the desk. I used to use it vertically with a dock. I am running it a few weeks now on a low stand, each monitor in its own TB3 output - without a dock.
This setup at least worked well. Now after the update to macOS 11, I noticed the fan was not doing anything - even with several apps open and a full Windows 10 VM with Domino, Notes, VS Code, Fork etc. running - no problem. I watched a Youtube video stream this evening when I noticed the silence. So the whole kernel_task hassle was just a software bug which took Apple almost a full year to fix - phew!
I am using Logitech peripherals: a K780 keyboard and a MX Anywhere 2 mouse. The latter had problems when using it with Bluetooth before so I used the USB-dongle. This buddy also had issues when used on a USB-C hub - it was just unusable. I bought an adapter USB-C to USB-A just to use the damn dongle on its own TB3 socket - that worked well. Now this is not needed anymore, the dongle works with my USB-C hubs - great! I so got a spare TB3 socket to connect e.g. my Samsung T5 external SSD.
I did a stress test this evening: running 4 (four) Windows 10 VMs in Parallels, all updating to the latest H2 release and one running the full stack mentioned above - the fan runs of course, but there are no lags or any other performance problems. This is how it should be with a computer with these specs.
Prior to the update on Friday I checked with another machine that run macOS 11 beta for a while if my music software is still running. In my case it's Logic Pro X with all kind of Native Instruments hard- and software (plugins). All worked well with the beta so I dared to update the main machine which is also my studio machine. No regrets, everything's running perfectly. Apple also updated Logic Pro X to 10.6.0 which I didn't check out, yet - but I will.
If you can, update to macOS 11, even though you may not like the new UI - and unless you do not use HCL Notes natively in macOS as this currently does not run. Updates will follow at the end of this months to fix this problem with 11.0.1FP2.