On the WATPW threads, running the script could overload the servers by fetching hundreds of posts at the same time which triggered a lot of errors and warnings.
Now, instead of fetching all replies at the same time, there is now a queue of replies it loads, by default 10 at a time with a 1sc delay between each batch. It prioritizes fetching subreplies for posts at the top, so it should not make that much a difference in the reading experience, and it took 30sc to fully load the 480 posts on the last post.
The number of posts and the delay can be customized with a config option