Performance optimizations:

1. Triangle rasterization: replaced loops over all the grid cells of the AABB with looping over the area of the triangle itself (i.e. bounds are set per row).
2. Region expansion: instead of sweeping through all the cells at each expandRegion() and finding the right level - sweep once per few levels and divide among several stacks. Left over are appended.

for details see:
https://groups.google.com/forum/#!topic/recastnavigation/xsEpMS3lFUI