You're piquing my curiosity on what could be causing such a difference between your i7-950 and an i7-4770K.
Do you happen to own Massive? If so, can you try the test mentioned in this thread (there is a link to the youtube video showing the basic idea in post #28 )
http://www.infekted.org/virus/showth...t=33532&page=3
I realize this test does not put Spire through it's paces, but this topic is of great interest to me. My current rig is an i7 870 which is overclocked slightly to 3.1Ghz. I am unaware of what any VST or host could do to achieve 3x-5x the performance on a newer generation CPU, but then again I haven't been following the latest and greatest CPU instruction additions and so forth.