I had the same problem. After using terminal.app exclusively for literally 13 years it became unstable and unusable for me on the new Touch Bar Mac and I switched to iTerm2. That is a noticeably slower program, especially with a big scroll back, but at least it's stable!
I have no idea what the cause of the instability was but I couldn't fix it and couldn't tolerate it.
I had a similar issue recently with a touch bar mac. It would crash pretty reliably when deleting lines during interactive rebases. This was in tmux with EDITOR=vim, hitting dd.
I have no idea what the cause of the instability was but I couldn't fix it and couldn't tolerate it.