Let's all come up with ideas for improving lag.

My idea
The passive ability of Class that gives a minor buff to the entire group for X seconds is overly updating its duration.
This is clearly one of the causes that makes the server heavy.
The duration of a passive ability that gives a minor buff to the entire group of a class is equal to permanent.
So it shouldn't be a problem to lose the duration.

Class group minor buff passive ability
you and your group members within 28 meters of you gain Minor X.

Change the following passive abilities as above.

Nightblade: Hemorrhage
Dragonknight: Mountain's Blessing
Templar: Illuminate
Sorcerer: Exploitation
Warden: Maturation