As a matter of fact, graphics can have a serious impact on performance, especially when you have a lot of floating windows with software and plug-ins not optimized for graphics performance. I quickly ran into this problem with my old MBP as it only had an integrated Intel HD GPU.
On my new machine, I disabled the graphics switching feature that would switch to the weak on-board GPU when the MBP feels it doesn't need the powerful GPU and can save some power. I have the power adapter plugged in most of the time anyways, and graphics performance shouldn't become the achilles heel with the powerful CPUs we can use today.
Oh my, I didn't realize that. I better get a new machine too then. I am currently in MBA with integrated Intel HD GPU, and its totally limited when it comes to East West orchestra (it is supposed to have around 3.5 GB memory but the graphic card takes up to 1.6 GB memory, leaving me around 2.2 GB ... sad).
Thanks for the correction Moritz!