[unnouinceput]

Looking at its inner working seems it's uses SQLite as storing. While a few hundred entries in any SQLite DB should be a breeze to parse and show under a second, maybe the person(s) involved in this project are not that DB proficient and made some rookie mistakes. Maybe they'll notice this and improve it's history speed as well, shouldn't be a problem for any SQL developer with a bit of experience in hands.

[alfu]

Based on this issue https://bitbucket.org/heldercorreia/speedcrunch/issues/746 (2017) it could also be re-highlighting the entire history when a new expression is evaluated.