Just my 2 cents, I don't know everything, but I'm fairly certain that some i7s would perform the same as an i5 with KSP... An i7 with 8 threads (4 cores?) can still only use 1 thread for physics, as with an i5. GHz (and other factors) would make more difference. Also, how FAST is your 1000 part ship running? Remember due to the delta-time slider setting, you can easily be at 30 FPS, but maybe running 4 or 5 times slower than real time. Because of this, I would recommend that OP should make sure his/her delta-time slider (found in the settings) is all the way to the right (because I just have a i5 2.8 GHz and still get 30 FPS with 700 parts, slow motion of course)..