This isn't real lag. Let me copypasta some stuff that really helped me.
This isn't lag at all. What you're experiencing is something new in SRB2 2.0, which is consistency failure protection.
In order to assure everybody in a netgame is playing the same game, the game runs consistency checks to maintain synchroneity between the players. In 1.09.4 and before, if the players were not synchronous, there was nothing the game could do to restore stability and thus the offending player was kicked out of the game, with the message "Consistency failure".
In 2.0, a console variable called consfailprotect was added. I'm not sure what its value really means, but while it's positive, instead of kicking players, what the game will try to do is restore the consistency of the game. How does it accomplish this? Easy. It sets all of the joiners' states to what the hosting client thinks they should be.
Some times this fixes the problem. Some times it does not. It may be due to differing versions between the host and the joiner, it may be due to slowdown on either end or it might very well just be the faulty netcode acting up. If the problem doesn't fix itself, there's two things you can do:
1) Disable consistency failure protection by typing "consfailprotect 0" in the console. The result will be what would happen in past versions of SRB2, all players unsynchronised with the host are kicked automatically. This is the worst solution, because even in recoverable consistency failures players will still be kicked.
OR
2) Turn the console variable, "blamecfail" on. While this has the issue of continuously spamming the console until the problem is solved, it points out EXACTLY who is responsible, allowing you to manually kick them via their player number (KICK # in the console). Remember to be kind while doing so.
Of course, if you aren't hoasting, or can't find servers, this isn't much help. make sure that the master server settings are right.
