I tend to crash after playing about 1-2 hours. I also crash when there is a zerg. Yesterday, I was fighting a world boss (I think it was Lyssa) and I crashed close to 20 times during the fight. It was really annoying. I think I need to avoid those types of fights. It might be also because of the screen resolution I play on. I am not playing on the highest (highest is like 2500 × ...) resolution. I play at 1900×...
My imac specs are:
27-inch: 3.2GHz
Specifications
3.2GHz quad-core Intel Core i5
Turbo Boost up to 3.6GHz
8GB (two 4GB) memory
1TB hard drive1
NVIDIA GeForce GT 755M with 1GB video memory