Very long render - a portrait and a crash why?

I was trying to do a comparison render of G9 and G8.1. At first I rendered G9. It took less than 5 minutes to render. Then I added a G8.1 character and rendered both together. Same lighting, same setup, etc. This render took 1 hour and 27 minutes. It is something with G8.1 I would assume. 
Going to shed the hair on G8.1 and see how that works. In the meantime I turned off G8.1 and rendered g9 in the same location: Time:3:43 . then i started a render with G9 and g8.1 without hair. It started and after 43 seconds it locked up. Then DS crashed and was gone. Someting totally messed up for sure.