I haven't tracked that much simultaneously myself yet, but have you seen the OP's specs? Seriously, dual SSDs in RAID 0 and a very recent higher end quad core I7. Considering that some pro systems regularly track like 180 tracks at 192KHz for hours and the required bandwidth of 72 tracks at 24/96 isn't even close to the limit of a regular HDD, I'd say something is wrong. This should be very achievable.

Check out the FlushWriteBeforeRead setting in Aud.ini. According to the documentation:
 
"The default setting [0] causes SONAR to perform disk reads (for audio playback) before attempting any disk writes (for audio recording). Overriding this value by setting it to 1 causes SONAR to attempt disk writes first. This yields the best results when you are attempting to record a large number of tracks at high latency."

Good find. I'm also wondering if this got resolved.

Anderton
Check out the FlushWriteBeforeRead setting in Aud.ini.

Where have I read about that before?