Slow performance with Monterey...

I have downloaded Monterey to my late 2014 mac Mini. (I was using OS Mojave) Everything seems to be incredibly slow and even doing a cut and paste in an email brought up the rainbow wheel. In fact it comes up with every task I have attempted. Advice please.

Opening apps: it seems to think about doing so before anything starts to happen.

I was asked to allow dropbox and the AE (?)server to control my computer. I declined.

There is a folder housing some of my files that could not be migrated to their new locations. I have reviewed them vis-a-vis their incompatibility with 64 bit requirements and deleted some. I've no idea what to do with the remainder. Could they be have an effect on performance while in the folder?

My I.D picture in the Bulls eye has disappeared today, although, it was visible immediately after the download and re-start.

In advance, thanks.