AE 2021 Much Slower Than Usual

[Mr. D teaches CTE]

AE 2021 was working fine last week, but now cannot make any change without dropping into "not responding".  It "thinks" for a minute or two and then accepts the change attempted.  I can only move a keyframe one-frame-at-a-time; only type one letter of text before it stops working.  I've restarted my project with new content on my local drive (not OneDrive), cleared my cache, all to no avail.  My students have also been experiencing this unworkable situation.

[Mr. D teaches CTE]

As a matter of information:  I'm using Windows 10 vers. 20H2, 64 bit OS, 16 GB RAM.

Students are on various platforms as we are still in "quarantine" status.

Since this has come on so suddenly, I'm hoping that this is a result of a recent update that can be tweaked...?