If you were to paint a small patch of paint fx and convert to poly and create a proxy for it like explained here, then duping some rows or otherwise spreading the proxy object around your scene (I like spPaint3D, you can down load it from creative crash). it shouldn't murder your RAM. Its what I did for the grass in my March challenge entry. Just remember to put the object in a layer before you start duping so you can hide stuff if or when the video card starts to struggle and avoid having to wade through a sloppy Outliner and organizing stuff later.