render particles as uniform volume

[yaohaosquall]

Hi everyone! I'm doing some water shots and I want to render a large number of particles for the spray pass. By rendering points as uniform volume I can get a nice result but it takes about an hour to even render a single frame,and that is unacceptable for a 350 frames long shot. It's a very close shot with about 10mil particles to render.I'm using ray tracing render and have turned down the volume and volume shadow quality to 0.15, set stochastic transparency to 10,still,it didn't change much. So does anyone have some good solutions to this,or some other way to render the spray pass?

thanks!