On my Mac, it took about one minute– and it leaves a window to say that it’s running open (“Working please wait”) the entire time that it’s running. If the script halts immediately, then it either failed to launch or crashed immediately. In this case, it looks like it failed to launch.
Testing on Windows, it looks like selections with more than about ~2000 objects fails to get transferred to extensions. If you can select 1900 (or so) objects at a time, you should be able to use either extension. If I understand correctly, this is because the platform-dependent implementation of python accepts a different number of command line arguments.
