shared albums missing from photos, slow boot up, slow safari and email.

Hi,

I have an iMac Retina 4K, 21.5 inch 2019 running Ventura 13.5.1. While working on photos, my shared albums all disappeared from my computer, although they can still be found on my iPads and iPhones. I have tried most of the obvious solutions listed, but have had no luck. Also lately, my computer has been slow to boot up, and extremely slow when accessing the internet or retrieving email.