Here is what worked for me after the Windows 10 2004 update made two of my computers run as slow as molasses.
(1) Boot in Safe Mode
(2) Delete everything in the Windows prefetch folder. The folder is usually at C:\Windows\Prefetch
(3) Reboot
Windows rebuilds the prefetch folder so deleting it will not do any harm. However, if you feel squeamish about deleting it, then rename it and create a new, empty prefetch folder in its place.
I spent hours on the first computer before stumbling onto this. When the Windows update, and slowness, hit the second computer I tried this fix first and it immediately sped up.
Hopefully, it will help you.
Will try it. Thanks much