Sometimes something can lock up a render regardless of settings.   I remember trying to render with one particular hair in P7, the entire render would finish execptt the hair which was taking way too long.  

Just to humour myself I replaced the hair with one of Quarker's as I recall and it rendered quickly.   I went back to the original hair and checked the materials - I  can only assume it was a bump map that I disconnected and rendered again much much faster.   In fact, it even looked better without that bump.  

So, some merchants might have needlessly overcomplicated a shader or something which could be causing your render to go so slowly.