KDialog PassivePopup

I’m running a BASH-Script, solving approx. two tasks per minute. Using KDialog PassivePopup I found, that timeout-duration < 1 second is not respected. In fact, the last PassivePopup appears, 50 seconds after the script has finished.
Any idea, how my my goal could be achieved? Thank you!

#+begin_src sh
  printf "Done: %s" "$WHATEVER"