I have a lot of item frames on my storage res, probably at least 50+. Whenever I go there, I get immense lag. I usually run on 20 fps (my computer sucks) but when I go there, I get 5 at best. My res is 3425 on smp2 if you wanted to go see what I am taking about.
If your computer isn't great I'd suggest either swapping out item frames for signs, or grouping chests I'm categories with minimal item frames. Just something I did cause my computer sucks too