Windows 11 slow down

Has anyone else experienced a massive slowdown running windows 11 compared to windows 10? I ran the exact same Ultra fractal file on my 2 computers, and the windows 11 computer is about 2.5x slower. With the faster RAM, SSD and CPU, I was expecting about a 2x increase on performance in the newer computer. Both computers are running the same version of Ultra fractal.
Although the newer computer (running windows 11), does edit 4K video about twice as fast as the older (windows 10) computer; I would still like to calculate some fractals on the newer computer.
What I tried;
Disabled nonessential apps running in background
removed McAfee antivirus
Disabled most apps running at startup
I even temporarily disabled Microsoft Real Time Virus checking; doing this can help video files to export faster.

What is your setting for the max thread amount on the new machine? I remember I had to increase it manually when I changed my CPU a while back.

Good suggestion Phillip. There really shouldn't be any difference between Windows 10 and 11 on the same hardware.