FPS Drops when minimized

Got an interesting problem, hoping to get some help because its rather annoying. First I'll list system specs.

2 x Dual-Core AMD Opteron 265 (1.8GHz)
4GB ECC DDR400 Kingston
BFG GeForce 7800GTX OC
Onboard Audio (Realtek AC'97)
Windows Vista Ultimate (32-bit)

I just installed and setup this system yesterday. All drivers and firmware is up to date, and Vista is fully updated.

So here's what happens. I launch GW, and everything is fine, high fps and looks great. Then I'll minimize GW to do something on my desktop, then go back to GW and my fps drops huge. In most towns I get around 90 to 120 fps. After minimizing and restoring the game, it drops to 15 to 30 fps, and will not go any higher than 30 fps. I have tried multiple video resolutions and settings. Video driver is set to Application Controlled for AA and AF. V-Sync is turned off. Nothing seems to fix the problem. Only resolution is to close GW completely and then re-start it.

And for all you Vista nay-sayers, I used to be running Windows XP Pro on this exact system and the same problem would occur. Again using current drivers and XP totally updated. GW is the only game this happens in. I can play other games and TAB back to windows and then back into the game with no fps problems.

I've included 2 screenshots showing the change. In this case its a loss of about 100 fps.

Before minimize:


After restore:


Any ideas?

Have you tried playing it for a bit while in Windowed mode? Personally my FPS jumps between 120+ and 40's constantly, seemingly regardless of what is on screen at the time, or what town I'm in.

Also, are you using Windows Vista? If you have the game windowed in Vista with the Aero effects turned on, that could seriously affect performance.

I have exactly the same problem as Arterio, and I can assure: Aero has nothing to do with it. Even when I disable Aero the problem occurs.