Ghostty is extremely performant. I had a bug in some concurrent software; when I added logging the bug would disappear because the threads acquiring the lock on STDERR was sufficient to make the bug go away. On Ghostty this happened fast enough that I was able to reproduce the bug.

Maybe I should have been writing everything to a file. ¯\_(ツ)_/¯ Anyway, I didn’t think of it at the time and Ghostty saved me.