Working in a large group tanks performance

I often work in large groups when doing city / building maps. To keep the building layers organized, each floor will be in its own group so I can toggle the group transparency on / off. Anytime I'm working in a group editing in 2k, it tanks performace to the point where it takes 5+ secs to pivot or even place a stamp. The lag gets worse the more you add to the group and the larger the group is.