I remember that very early during the forum migration to SBS we had
removed the "Similar discussions" widget from the forum threads due to
performance reasons. That was good thing to do by the way since it was
slowing down the threads way too much. We had done the same for the wiki
articles too but had left a "Get similar content" link in the "More Like
This" widget for the wiki. That way someone can explicitly fetch that
data if he/she wishes. Can the same be done for the forum threads too?
Show a "Get similar content/discussion" link at the top of the thread
perhaps?