I have two issues...

1. When I play for a while my lag grows and grows until I have to re-log, which solves the issue. That should not be the case however.

2. When I go to any of Vanaduke's levels I instantly lag, forever.

I play the game on lowest settings with compatibility mode enabled. I can run SC2 and WoW with out a hitch. I understand its a completely different beast, but what I am trying to say is, I dont think its a hardware issue.

Something to note is that I feel like my lag SUBSTANTIALLY increases when more people are in the group. Two seems perfect, but when all four are running around, the lag spikes start.

This is a Macbook Pro...
2.53 Ghz Intel Core 2 Duo 4GB Ram
1067 Mhz DDr3
NVidia GeForce 9400M
Snow Leopard Operating System

I really enjoy this game, but the lag is holding the experience back. It is destroying this for me, and seemingly many others. Unfortunately I will stop playing this game if I cant resolve the lag, simply because it is negative fun to try and complete anything remotely difficult in this game through lag. Hope I can get some light shed on this issue, for the sake of laggers everywhere. Thanks for the time and consideration.