Audio Dropouts w/multiple audio tracks


For some reason, when I have mix projects that are about 20 or 25+ audio tracks, I get audio dropouts every once in a while when moving around the project. I’m currently running 6.5.1 32bit on Windows 7 64, Core i7 920 2.66 quad core, 9 gig ram. My sound card is the MR 816CSX running at 256. I have a 650 gig drive for my system and programs and a brand new 1tb drive that i record my projects to. However, this has always been my experience going back to Cubase 5 even on my Vista system with older drives as well. Even with no plugins, I would experience the same thing. It’s not to a point where i can’t work in it but its def an annoyance. Any suggestions? Thanks!