Essentially just a load issue.  I was running some profiling today (DB was getting slow), and about 98% of its load was coming from the block lookups (we don't save them separately, so looking them up was digging through the entire shares table), and with people scraping that page, was absolutely raping the db.  Getting rid of it today dropped load from ~4 on the DB to ~0.8 (huge!)

I'd love to add it back, just gotta come up with a nicer way to store it, and move the old stuff into the new system.