Under the "Discussion" preferences, there are two options I've found helpful:
The first is "Retrieve (few|more|many) comments". I think "many" is the new default, and "few" was the old default. The switch is probably why turning it off and then back on loads all of the comments.
The second is "Get (highest rated|oldest) comments first". The default is "highest rated", which causes it to load the best comments, but then it scrambles to dynamically stuff subsequent comments where they fit. Switching to "oldest" loads the comments in order, eliminating the script that arranges things. This has reduced my load time to a few seconds, an improvement over almost a minute, excluded hanging scripts.
(Of course, if that doesn't help, there's always "Enable dynamic discussions = false"