man22hog

Do you only experience the lag whenever you're on pvp?

Or do you experience it as well when you're on different location? say for example green despair? or maybe the trading channel which consist tons of people around you, do you experience the lag there?

If you already disabled firewall and antivirus, possible problem is... it's either the connection or your computer.

Try doing pvp on other channel with less players connected to it, it'll help.