Are there any guidelines to prevent slowdown in loading large Discussions?

I am asking on behalf of a faculty person who has experienced slowdown loading a discussion topic. The students were embedding a Padlet iframe which was fine, but once they started replying to each others' posts she experienced slowdown. In the topic there are about 40 original posts with about 20 replies each, for a total of 800 posts. For future posts, it seems to make sense to break up the discussion into 4-5 topics, and use links instead of embeds, but she wanted to check if there were explicit best practices. Thank you!