MacBook Pro (Retina, 13-inch, Early 2015)
2,7 GHz 2‑core processor Intel Core i5
8 GB 1867 MHz DDR3
Intel Iris Graphics 6100 1536 MB
detaching dock
detaching external screen
restarting the system (sometimes it solved the problem for some hours)
closed all safari tabs (it was helping a bit)
moved thunderbolt cables to other side of laptop
checked with Intel Power Gadget the performance
checked activity log, top etc (no evidence)
installed temp monitoring, nothing special
cleaned all caches with OnyX
reset SMC
reset NVRAM or PRAM
MacBook Pro (15-inch, 2018)
2.6 GHz 6-Core Intel Core i7
32 GB 2400 MHz DDR4
Radeon Pro 560X 4 GB
I unplugged a Lenovo Thunderbolt dock I had been using. This finally dropped off utilization which was being eaten by a kernel process.
I finally did a hard reset (held power button down until Mac just shut off) - rebooted.
I manually removed as many old / unused and incompatible / 32bit apps and audio drivers etc etc as I could find that might be somehow conflicting with the Big Sur architecture.
I downloaded Litte Snitch and blocked ocsp.apple.com from within the trusted folder
I removed all USB peripherals such as USB audio interfaces etc / printer / USB drives and performed a SRAM reset on my main internal SSD.
I also have a secondary internal SSD so booted from that and performed another SRAM reset on it, too.
Enable reduce motion through accessibility (This will help reduce or perhaps fully stop your map from lagging. If you still face slowing/lagging/glitching issues, you can also reduce transparency which will help for sure but won't look as good).
Make sure to get CleanMyMac and run all of its free programs (You can also get paid version if you want)
If you just recently updated to macOS Big Sur and you feel the Mac is slower than usual, the best course of action is to keep the Mac awake, plugged in (if it’s a laptop), and let it sit for a while (perhaps overnight or for a nights) – basically, hurry up and wait. I know that sounds like weird advice, but here’s the logic behind it: after a major macOS system software update, the Mac performs various maintenance routines behind the scenes, it reindexes the drive for Spotlight and Siri and apps like Photos may reindex too. So basically, let the Mac sit turned on overnight, perhaps for a few nights in a row, and allow those indexing and optimization processes to complete. When they’re finished, the performance of the Mac should be significantly better, if not entirely back to normal. This is often the number one reasons Mac users think a new operating system is slower than a prior version, so don’t disregard this simple advice!
You should also get firefox instead of using chrome (if you do) because chrome can slow your mac very much and plays key part, especially on Mac Big Sur. Firefox is one of the Top 3 browsers and it's very smooth.
I've changed from using the internal HDMI port to a mini-display adapter - i can now get my external monitor reconnected and it's isn't taking 100% of the CPU
I've reverted back to allowing the os to control the fans rather than 3rd part app - and after a short burst from the fans to drop the temp down from about a 65degrees to 50, its' gone back to running fine.