Dashboard and other admin functions running slow or not at all

Hello. Looking for some help related to admin side of my wordpress site

Just over 2 months ago my dashboard started acting up when creating posts and adding photos.

At first I was creating gallery’s in Fancy Gallery (Rafael Dery Plugin, writing a post and inserting the gallery into the post. You can see an example at this link: https://kevindalyphotography.com/vanessasly-engagement/

Fancy Gallery started acting up so I started adding photos to a post via the “add media” and that worked for a couple days but now it’s working on and off. In the last 2 weeks I’ve tried using “add Media” and I’m only able to add 3-4 photos at one time and sometimes nothing loads at all…. the page just sits there. After waiting 10 Min I try updating the page and nothing has changes when the page updates.

The average photo is 400-700 kb in size

Any suggestions on how to fix this?

Also – If I deactivate the Fancy Gallery will all my past gallery’s be lost?

Kevin Daly