If you know that the result will not change over frames, blitting a cached image will always be faster than re-rendering. It's not necessarily a need, just an improvement. That said pathfinder is fast enough already that it can deal with rendering interesting workloads every frames at 60fps, and will keep getting better at it, I think that there is room for improvement in the tiling phase.

I would like to eventually add the option to cache masks in a texture. I think this should probably be an option for the user and not something I do behind the user's back unless the user explicitly opts into heuristics, though.