I spoke to NVIDIA about PhysX triangle mesh cook times. They mentioned that there are some flags you can set in C++ to improve cook times. From their number, setting PxMeshCookingHint::eCOOKING_PERFORMANCE seems to make things about 4x times. You can also use eDISABLE_CLEAN_MESH and eDISABLE_ACTIVE_EDGES_PRECOMPUTE which together give another approx 2x speed up. Note that this might impact quality of physics simulation collision with the mesh though.
I’m going to add a task for us to expose this as an option on ProceduralMeshComponent, so users can set it when doing lots of runtime collision creation.