So I did some more work on that same code after mark touched it. It turns out that that preload_rows() call was a big problem--the implementation was that in order to see if we had any more comments to load, it scanned through all of the comments that had been touched on that request to see if any hadn't been loaded yet. Now, the method that mark modified was also scanning through all of the loaded comments to check for a different setting... So by having that nested call to preload_rows in there, that moved it from checking n comments to checking n^2 comments. Very very bad.

I don't remember if I fixed that in the update that I made, but it's certainly a fixable issue. If the calls to nodeid() (and therefore preload_rows()) is cheap, then calling nodeid() vs. $_->{nodeid} shouldn't make that much difference. I mean, it'll make some, and if you're really seriously optimizing that could be worth it, but chances are there's some other underlying problem.