I am one of the many players who has a decent amount of lag and latency on SK. Most notably in FSC.

The snarby shadow lair. What can i say. 90% of it was easily twice as laggy as the worst parts of FSC. Be forewarned.
3 occasions my teammates went floating into 'outerspace' outside of the maps. Followed by litearally 1-2 minutes of lag time stops. I could move around, but not break any blocks, not talk to my teammates, everyone else is frozen or endlessly walking in their last direction.

This is caused in great part do to new 'cool ambience effects added into the levels. More than ever we need a way to turn this off, in these new toughest dungeons. Parts were mostly unplayable, where i had to rely on my teammates to do the work. 2 of us were having this problem (our worst lag ever). Another who doesn't have usual lag issues was having his 'worst lag ever' but not as bad as me and the other guy. And one guy who never has lag was having his 'worst lag ever' but very playable (i assume something like us usual laggers experience in FSC).