I have a user script for that [1]. If you visited a story's comments before, it will highlight new comments and can auto-collapse threads without new comments.

I have a user script for that [1]. If you visited a story's comments before, it will highlight new comments and can auto-collapse threads without new comments. Otherwise, it gives you a slider you can use to highlight the X most recent comments. [1] https://greasyfork.org/en/scripts/18066-hn-comment-trees https://greasyfork.org/en/scripts/18066-hn-comment-trees