Like others have said, the Cinematic Studio stuff is pretty light on CPU and RAM. BBCSO seems acceptable if you don't have everything open at once. I might be imagining it, but I remember BBCSO being far more taxing on my system at launch, so maybe the updates helped. If you're only using Core, this should even more of a non-issue since the mics seem to be the most taxing on the CPU.
I personally hate keyswitches, though (because it messes with my mixing process), so I bring a lot of the resource problems upon myself. It's a tough life....