Ah yes, but I could defiantly understand why with your forums VirtueTechy--they're massive
Then again, this version of the hack is more improved from the last, in the major effect that it will compare threads to the current thread viewing until it has gathered whatever you set as "LIMIT", in your case 4. (in contrast to the old version where it would retrieve ALL threads, then compare). Not to mention, your forum must have dozens of threads with similar titles, so this hack shouldn't have a problem finding 4 similar threads and quickly. Then again, each similar thread could be seperated by 300 non-similar threads, thus having to read more.
This hack still proves very useful for the smaller forums, such as mine with 1,938 threads and not the slightest decrease in performance.