After uninstalling just one program and then re-launching Uninstalr, it reported the following statistics:
414 programs found occupying 24 GB.
985 files, 528 folders 45262 registry keys, 14805 registry entries.
Analysis took 198 seconds.
In all these tests, Uninstalr was the only program being launched.
ADDITIONAL REQUEST: The checkbox option to kill presently running programs seems to be kill ALL running programs, or kill nothing. It might be helpful to have an option to kill ONLY the running programs being selected for uninstall.