Actually I have noticed a significant increase in background mixing speed. Loading up old mixes is much quicker now. Also love the track eq which doesn't seem to slow down the computer at all. However, as others have said, the realtime effects will slow things down a bit. But that happens with all other realtime software so no big deal.
This may be of some interest to some of you.
I've been using my joemeek gear to compress things in realtime with great results. What I do is I send all the drum tracks to play out through a different sterio pair. My soundcard has 6 output channels or 3 sterio pairs. So instead of them playing out through the default "out1" they go out the "out2". I then run cables from my soundcards out 2 to the joemeeks input and then from the meeks output back into 2 new recorded chanels. Now since my soundcard is only playing back whats coming out of the stereo "out1" for all tracks, this eliminates the drums (now going "out2") from being heard. But If I turn on solo on the two tracks the meek is about to be recorded into, you turn this on in your soundcards software mixer, now I can hear the stereo compressed drum tracks with the rest of the mix and without hearing the original drum tracks. So I can tweek the compression settings on the outboard meek while its playing back. Fucking awsome. Once Im happy with the sound I can just record them. This can be done with any tracks. I've actually re-recorded guitar tracks the same way but through a wah wah footpeddle.