IMac running very slowly with Catalina
I have an iMac (Retina 4K, 21.5-inch, Late 2015) running 10.15.1 with 16 Gbytes memory and 29 years experience.
The machine is unacceptably slow in logging in; switching between the two registered users; loading applications; time machine backups etc.
I've looked at Activity Monitor, nothing hogging CPU or memory and I've rebooted in Recovery mode in order to fully run Disk First Aid. That didn't help, in fact on restart and logging in to my user account I saw a totally black screen with a cursor, then the spinning beach ball for about 10 minutes before FINALLY getting into my account.
Any ideas?
iMac 21.5", macOS 10.15