
I have upgraded my system to Monterey, my Lightroom is running with no slowdowns. Certainly not the fastest as a thunderbolt connection would be quicker but couldn't find the dock with the right thunderbolt connector. I got another 1 tb ssd and copied everything onto it and made it a boot drive, it is connected by the USB port on the back of the iMac. I had a shop put in a 1tb ssd but sadly that one was still intermittent so I suspect the controller.

I have a late 2015 iMac with 32gb memory that had a 2tb fusion drive that I replaced as the drive was my problem.
