And what are your processing times like? I use my Mac for video editing, but I have never had any problems doing that smoothly even on much weaker Macs.

Only issue I have on Mac is compiling large programs.

The issue is with live streams of audio or virtual instruments with CPU heavy effects with very small amount of buffering (typically 64 samples @ 48kHz, which is 0.75ms). Also processing of instruments and effects for one track (+ relevant busses) has to be in series so more cores doesn't help a resource hungry signal chain. But of course they do greatly help overall effect/instrument count over many tracks.