You probably have Windows updates that need installed.  Restart the machine and take updates.  

I have the latest Windows update. 

This particular is not always easy to troubleshoot. Do you remember changing anything in the environment that caused it to be slow?  Could be the Windows update caused it to be slow.

You can try some of these suggestions below and give us back a reply. Also is a PDF for various suggestions.Performance Issues on Stand alone or network.pdf

Exit Sage completely. If you have an antivirus try to disable it. Turn off the User Account Control to never notify (search for UAC). If that does not improve performance you can reboot in selective startup. or it may be slow because you have very large files inside of Sage, Help, support utilities, file statistics (version 2019) (above 2 gigs).

If you are on a network does any other workstation have that problem? If you use a User ID in Sage to log in, you may need to set up a new User ID.