Preview render is instant, cant render whole scene

Hey guys i have two 780s running, and I have a nature scene with some grass, a tree, and pond below the tree. I can set the viewport to live preview (in cycles) and render out 50 samples in 7 seconds, and i can do everything fast and efficiently, but when i press render, it takes a minute to copy all the stuff to the and load the BVH or whatever, then the actual rending process takes forever, why does a complex scene with a lot of particles doing this? i pressed render and came back 3 mintes later and almost nothing had happened.

I don’t use cycles and know very little about it but I would venture that it has something to do with the difference between your displayed # of children and your rendered # of children. You also might have your rendering samples set far higher than your preview samples (which only makes good sense). Combining those two could yield a double exponential difference in render time. Most folks don’t seem to worry too much about cycles render times though since quality takes time.

Hi, also render settings in preview are different to final render, subsurf for example.
Keep it as low as possible.

Cheers, mib.