Huh. So it was mostly paranoid unicode handling and not syncing?
Works fine for me, ~5MB hexdump file cating time is down to ~1.5 minutes from ~1 hour before the fix. vim also starts up instantly now. Could be faster, but at that point human is the bottleneck most of the time.

Still, it's a stopgap, and the other code path still needs to be optimized. Suggest keeping the issue open until then.

@michalbednarski Sorry for the delay here! Looks interesting, nice gains without messing up the code.

I think mHasNonOneWidthOrSurrogateChars should be reset to false the clear() method, since otherwise over time all rows will end up having this set to true (as lines are reused after a while in the circular buffer).

Rebased and added to flag reset to clear.

Thanks! This will be in v0.62 of the app, to be released in a few days.