For fastest speeds, the system needs to minimize copying to and from the video card. This example demonstrates several methods for minimizing copying.
Turns off DOPs caching. Caching requires copying all the fields every frame. Useful if you want to scrub and inspect random fields, not if you want maximum speed.
Only imports density to SOPs. This means copying only one field from the GPU to CPU each frame.
Saves to disk in background. This gives you the best throughput.
Uses a plain Smoke solver.
Displaying the simulated output in the viewport requires a GPU → CPU → GPU round trip, but this is required in general to support simulating on a card other than your display card.