I found definitely a easy fix for this problem i tried 3 times and worked every time
here the steps: 1-Log in on the character with the lag 2-Disconnect from this character back to the world choosing page 3-Wait till the lag goes away (the lag keep even on this screen, you can check it by moving the mouse around and notice the stuttering) (may take up to 10 min) 4-Log in back on the same character after the mouse stoped stuttering on the menu, now you can successfully join a channel on the Chat menu
