My specs:

I7 4770k
GTX 760
8 Gigs of ram
Win 7 64 bits

Many times when I'm near the market or crystals in cities with many people around my framerate takes a big hit and goes down from 60 to 30's or 40's.

In the open world my framerate is 99% of the time 60 fps steady.. my temps are really low so that's nor the problem.. latest drivers also

Is this normal? or it's only my problem?