Typing too fast when searching help index with ctrl+k gives no results

When I use the help index via the ctrl+k locator, like
ctrl+k, ? ComboBox
and type this too fast, there are no results turning up.

I have to type this very slowly, one letter per second or so, to actually get results, as the search/filter algorithm is not able to keep up. If I type another letter before the small busy-spinner disappears, the list is empty and I have to go back (backspace) until the results turn up again.

At least, I think the filtering needs to be re-applied again after typing has ended, maybe wait half a second or so after last key event. It does not handle a new key event properly when received before the last process was finished.