I have a lot of symbols that use gradients which end up slowing down performance. Is there any way to disable illustrator from rendering items when they are turned off? It seems that even when I make them not visible illustrator still runs slowly which is why I believe it still does massive amounts of calculations even when they're turned off.
In the Layers Panel flyout menu choose "Panel Options" and turn off thumbnails. Rendering those thumbnails can slow AI to a crawl, and that's what's giving you the problem here.