Very Long Save Time

I experience frustrating very long save time on Projects: Cubase 7.5.4 on Windows 7 64 bit Xeon Multicore 32Gb RAM.
I have a big rig with about 50 analog inputs/output (a stack of 6 MOTU boards) and couple of VST (EZDurmmer and Halion) and and external module (Roland Integra).The MOTU I/Os are all mapped in the VST Connections tab.
I have about 10 midi input from keyboards and other devices i use as input.
No mixing outboards or controllers (I use 2 22’ inches touch screens).
The average Project is about 60 channels.
Everything is fine when the Project is open, but when I go to save it is incredibly slow: it takes about 2 minutes or more.
Even if I cut the number of tracks to 20, it sticks on long save times.

Is there a way to debug the root causes of this?