I thought I should try the latest version of st in git, as lots of fun activity has happened.
So this is a weird one. I often have my monitor vertical, using 'xrandr -o left', as that is clearly superior. However the newer versions of st, using XFT, are very slow at refreshing when things are in this mode. It takes around 0.3 seconds (guess) to refresh, so things don't catch up with typing well at all. CPU usage goes up to 100% while typing (with top reporting XOrg as the offender). Things are fine if I have a small window ~5 rows high, but not when I have one of about 30. This didn't happen with earlier revisions of st; all the releases not using xft are fine, and an earlier checkout I have from when xft support was still in a branch (56d8f361918d) also works fine (that's about a year old, though...) I could bisect I suppose, to find the offending commit, but if anyone has any clues, similar experiences, or ideas of where to look in the code, I'd be happy to do so. I suspect this has been around for a while, as ISTR bumping into it a while ago, but I didn't look into it then. My bad. Nick