Some may have known this for ages, this may be new to others. Pages that get much over 50 to 100 comments, loading comments starts to get glitchy, the level of how glitchy varies between users, but this is not a new problem. This has been a problem since forever. Well ok, forever's a long time xD since 2011 when pages started accumulating lots of comments.
I could bore you with the nitty gritty details of 'why' this happens, but part of the problem is using templates in comments. It's a double edged sword. On one hand, because user's have more than one character, using templates helps people to better see which character is being rp'd and to read through easier who talks when.
One way you can help start to slow this problem down a bit, is to change how you use your templates.
Instead of doing it the normal way:
simply do this instead:
adding in that extra subst: changes the way templates load, and should at least help the problem.