Currently they are disabled on Heyuri's /b/ for this reason. I don't know how much work is needed to improve it (possibly a rewrite even), but it should work without slowing down the posting process this much
From an old discussion:
This was the case with a Koko instance with a lot of posts with replies.
Specifically where the USE_BACKLINK is used.
For every post, it spams the searchPost() in koko.php to check if a post has replies and list all of it.
Potential Solution: Use the results from the DB once instead of querying it over and over.
Currently they are disabled on Heyuri's /b/ for this reason. I don't know how much work is needed to improve it (possibly a rewrite even), but it should work without slowing down the posting process this much
From an old discussion: