Read a thread by Axis, the main programmer behind Day of Defeat, and he mentioned a few problems with 2.0 that are being fixed for the 2.1 version, notably:
"1.) Map Changes Lag\kick you from game - This is b\c of the fact in the coding it was sending alot of scoreboard info to everyone. Redundant coding, basically I would send all my info to all 32 peeps on the server, then each of them would send theirs out to us as well. You had literally 32 peeps sending out info to each person. 32 x 32 = you get the picture. Now that coding was getting called 2-3 times, so anyone wanna geuss why it was lagging ? Not only was it getting called 1 time, but it got passed and called 2-3 times. Now Mugsy found even more lag problems with the map changes dealing with too much info, ect being sent. So all in all we have really knocked alot of network flow out for 2.1.
2.) Random Game Lag\Overflows - Following the same concept as above, basically in the spawn coding for each player there was the same problems. WAY too much info being sent 1-2 times for each person spawning, which was sent to all peeps on the server. So everytime someone spawned they would shout out to everyone alot of info. All fixed so far for 2.1. "
And, my favorite:
"Water Snipers are out for 2.1 "
