Windows 11 very slow

I have been running a digital audio workstation for years (since win xp). About 2 or 3 updates ago things started to slow down. Disc access became sluggish. I noticed there was very high cpu usage, sometimes maxing out. When I looked in the task manager to see what was goin on I saw that a procedure called Extended File Copy was using sometimes up to 50% of my cpu time. That's new. When I shut it down it would come back up ok but a few minutes later (regardless of what i was doing) it would be hogging cpu time again. Since then it has become so bad that I started suspecting a virus so I ran all the offline virus scans and they all came up clean. The computer was just hanging continually whenever it tried to do any disc access. For me this is very bad. I'm losing money that i can't afford to lose. Today I decide to start from scratch and do a clean install so I move all my personal files etc... to another drive, and load a USB drive with the install files from the microsoft website. Well go figure, I still have the same problem. It's not a hardware problem, I just put a brand new drive in the system, and looking at the posts on this subject from around the internet, there sure is a lot of people having the same problem as I am. They are all being told the same thing, disable all startup apps, check for a virus, boot in safe mode bla bla bla. This used to work and with basically no change on my end, but the endless barrage of updates from microsoft, and now I can't do my job. As far as I can tell, every so-called improvement to the operating system just keeps making it less functional. Now it is non functional. Perhaps someone from microsoft could solve this. If not their product is useless.