Steve.
some of my bb stats....useing my old i5.
1. 100 bars bb mix to stereo wav...40 secs.
2. boot into bb from win desktop..4 secs at most.
3. regen a trak ...same as 2 , 4 secs at most.
4. cliking >+ regen button or double clicking on a bar ,
same deal mate 4 secs or less.
ps i reckon what happens with regens is the low level bb code is prolly filling a few buffers then starts playing ..ie advanced look ahead buffer mgt // programming.
thus creating illusion of speed , similar to what mainstream daw multitraks do....fill buffers etc.
happiness/cheers.
om