I am having the same exact issues and now that I just updated SU it has gotten worse. I believe that the true issue lies when SU and Vray loads their materials while starting. Sometimes there is a discrepancy between materials in SU and Vray and this normally makes my SU files to crash. My problem is that I need these programs for work, I am expected to get my renders done and it is extremely frustrating when it takes 30 min's to open one file.
I am trying to contact Vray for assistance because this is totally unacceptable but in the mean time does anyone have any ideas as to what I can do?