I've been having some issues building my 4x4 world. The problem would be fixed with an option to limit how many concurrent builds are active at once. My home computer can handle building 4 tiles at once, so right now I have to manually set up 4 separate builds. I'd like to run the thing over night except I can't since I have to be there to set up the next build when the previous one finishes. It would be great if I could tell WM to render all tiles but only render 4 at a time.