MacPro, dual Xeon, 16 threads, ATI HD 5870.
Broken: (example: 2.69.7 4b206af, see splash screen)
Worked: All recent buildbot 2.7x, all my builds as well, all working fine
lagging when stroking, even on a 5k mesh.
No need to use multires, no modifiers.
Same lagging under dyntopo, (nothing to do with dyntopo though, irrelevant to the density of the mesh)
I don't know how to build a blender that supports OpenMP, neither buildbot uploads support Open MP, this is well known.
The official 2.7 supports OpenMP, as seen in console.