[Yuki Maru Hoshi]

I say take the pressure off the database, strip the silly social groups feature since it's underused plugin and instead install a plugin the write to DB alerts alerts for when people are quoted in threads on the forum... oh and update vBulletin. Not sure if the latest vB has PHP7 support or not, but updating it to support that alone could potentially increase performance and maybe help out with reducing server costs so may be worth it in the longrun to update. (plus more secure)