Search gives up on small strings

Hi!

I experience the following weird behaviour: sometimes, when I'm typing small words (I've figured out `helm-org-rifle` only works with words of length >2 (or is it for occur only?)) the search behaves as if it times out. Sometimes it's possible to revive/restart it, sometimes not. It seems to happen mostly with I'm typing in russian, which is weird... maybe `grep`ping unicode is more time consuming? If I use search for some time, the problem seems to partially disappear, which makes me think again there's some caching going on which speeds up search.

Anyway, here's what happens without my unnecessary hypotheses; for example:
1. I call `helm-org-rifle` and type e.g. "math".
2. Nothing happens. The cursor blinks. The window shows no results.
3. I type "e" so that I see "mathe"; this brings many results that are related to "mathematics", of course.
4. I erase "e" again. Sometimes the results page still shows the previous results. Sometimes it becomes empty. Sometimes it actually does what it does -- outputs all the necessary results.

Also:
- I don't seem to experience this with `helm-org-rifle-occur`; it sometimes waits for about 3-4 secs on my short words, but gives me output. It seems that the words that this bug occurs on take quite a lot time in `helm-org-rifle-occur`.
- I *do* have the same problems with `helm-org-ql-agenda-files`. But it seems to work slightly better: sometimes when I run `ql` instead of `rifle` on the same string it succeeds. But `ql` also fails on some strings similarly.

TLDR: sometimes I type something and don't get any results. When I re-type it, or add and remove letters, sometimes, it begins to work.