Since last night i, and my crew were getting some horrid block roll back and its making construction/farming next to impossible as we take out at 20 blocks just to have 15 of them re-appear on us. And seeing as it was 5 people all getting at the same point in time i think it safe to rule out the issues being on my end.
All the new players go their first, and mess around. Then they migrate elsewhere. But the lag is from so many new people, and that a lot of them are probably digging.
currently there's only 19 people logged on to smp9, i've seen as many as 40 players on be4 and never had lag this badly. i don't think it has to do with the amount of players online atm.