I frequently come across models that have an excessive hierarchy of unnecessary limbs. This causes rendering to be slower and memory usage to be higher than it needs to be. If great numbers of the model are used in the scene, these problems can be significant. The windmill model below contains a pretty complex hierarchy.

A new tool is being added in the model editor to collapse all limbs of a model into a single object. Select the Tools > Collapse menu item and your model will be optimized:

This model needs a little more work so we're going to calculate some new normals for it:

And then we'll add an automatically generated physics shape to it:

This feature will be included in the next build.