Hi,
I recently downloaded the 1.5 demo for Mac Os X, hoping that the CPU usage when using VST instruments had improved from earlier Release Candidates. I was dissapointed to conlude that there were no improvements. On my PowerBook G4 1.25GHz, audio turns choppy after just 5-6 tracks with VST instruments (IMPOscar). I did a fast comparison to Logic where the CPU usage for the same configuraion were lower of magnitudes.
Is a fix for this coming? Unfortunately the software is not very useful in the current state, a pity since the other stuff seems to work really well 
/Pontus