Reducing the build part of the rendertime

I hope I have the right name for this…

So - when you render an image there are two stages: first of all it builds the scene into the render engine (if there’s a better name for this please let me know) … well, most of the scenes we work on are outside, meaning they render quite fast, however they often contain particle grass and microdisplacement so they build very slowly. Often, the build time is nearly as long if not longer than the rendertime… we are all looking forward to 2.8 and Eevee to land (we want to wait for it to be actually out before we move the studio over to it) but what good is rendering in 3 seconds if it still takes 1 min 30 to build the frame?

Dues anyone have advice for speeding up build times? Are there ways in which Blender doesn’t have to build every frame of an animation? Is building the correct term?

Optimize particles, if that’s grass - reduce drawing steps perhaps, reduce geometry complexity, reduce microdisplacement dicing scale…
If you have huge microdisplacement and a lot of particles you won’t speed it up really.