Правильные программисты пишут правильные тулзы:
Ok. So the UDK has released there 2012 version and the first thing I see is this,
Simplygon Mesh Proxy Tool
New Simplygon Merge Tool for combining static meshes
Grouped static meshes can be combined into a single static mesh
This can greatly improve rendering performance
Materials/textures are automatically collapsed and new UVs are generated
This tool is fully "non-destructive" - you can modify meshes and remerge, and roll back changes if needed