Re: everyone impressed by how fluid it is with multitouch: The number of touch points doesn't affect the performance of a grid simulation. Using 10 fingers just sets high values at more places in the initial grid. The effort to solve each time step is the same after that. The computational effort scales with the resolution, not the boundary conditions/input.
It could be in part because the default settings don't let you see the persistent levels of turbulence throughout the entire grid. Set the density to .996 and velocity to 1 and vorticity high and you'll see just how crazy it can get.
