Rendering Problem

Can any one pleas tell me, why does rendering current frame take such a long time? Yes i do understand i’m working with fluids, and their on subsurf and multires levels 7, but at the same time i have Quad Core, 4GB of Ram. So pleas tell me am i doing anything wrong? It takes like an hour to render one frame for me to see what i’ve done, and its on 1000x600, 8-bit. Any one finds a solution let me know as fast as possible. Thanx

I think that’s where the problem is. Something as simple as a cube (8 vertices) gets 24578 vertices with 7 levels of multires, and then multiply by 4 for each level of subsurf, that’s an insane amount of vertices for such a thing.