If i put my server in CW mode it laggs to death?

[Mambo]

If i put my server in CW mode it laggs to death yes..
Cause i can login and stuff normally and the first 10 mins i can play normally to but after that text isnt showing when i type it, channels aren't showing so.. BIG LAGG

Any clue why this is?
(Btw, if my server is in normal mode > NO LAGG)