Sort by thread title is very expensive for "AI" crawlers to hammer at

[XFdestek]

I've had a couple cases where clients have been significantly impacted by crawlers hammering at an XF forum view with a non-default sort option. By far the worst is the sort by thread title option.

I'm not sure what the best solution, but for my clients; bespoke disabled custom sorts for guests/robots while allowing it for members has been a significant performance saving.