Composite materials and site question

[Tommy L]

Do composite materials with lots of alpha channels bump up render times? Or am i best modelling window frames / sills etc? This is for an external animation in viz. Also, whats the best way of modelling fairly complex sites with lots of smooth level changes (country estate)? Ive tried a noise map of the terrain in the mesh displacement, but the render times went through the roof, and that was on a little bit of grass. Soft selection seems to inaccurate, am i missing something?

Cheers, Tom.