Nope, today even worse. 1 minute (about 60 proofs) from every single mob, then 20 min of nothing, then 1 minute again... got ~200 proofs in 1 hr. And regaring letters, same issue nothing for 5min, then 3-5ppl get runes instantly. I doubt that 1 mob can drop 5 runes.. If all this stuff is going through database tables, it seems that problem is in drop queues. Database sleeps, calculates, it needs to expand, but it's busy. For this to work devs need to allocate more table space instead of letting db grow all the time.
If it's not the issue, check gm buffs, 5ppl in party had it