I recently installed win10 on a 2019 Lenovo thinkpad x1 carbon, and it has similar issues. I don’t use it much, but I’ve wondered how much bloatware is affecting the cpu usage and therefore can speeds. It was running Ubuntu Linux before and while the fan came on sometimes, it was less often and less pronounced.
You could try a live Linux usb to see if you get similar results, that would point to a software issue.