I don't know if it of any help, but after replacing my video card with a higher model (pair of 6800s running at 800 by 600 with everything on the lowest settings to a 8800gt running at 1440 by 1050 running at the highest settings) this problem has gotten much worse for me.
Previously, I would have 1 or 2 very short "action freezes" per wave where everything would seem to stop for like 1 to 1.5 seconds.
Now the "action freezes" seem to be 2 to 3 per wave and they last about 4 or 5 seconds each.
There have not been any other major changes on my end except that I'm now high enough level that its not instant death, even if im standing among some monsters.
Core 2 DUO @ 4.1Ghz Grizzled_AM AM 43
Nvidia 9800 1g Grizzled_EMT. MM 85
4gb mem Grizzled_LW WM 87
Grizzled_EN EN 64
A drop of knowledge is more powerful than a sea of force~ unknown