Lag, as soon as game start menu

Details:
The game hangs for about 5 seconds every 15 seconds. That starts as soon as i get into fullscreen. In the character selection, if it hangs, the 3D view still works and is animated only the 2D GUI is hanging.
Steps:
1: Start the game
Date & Time: In beta and then the first release version it was fine, then with on patch (forgot wich) it started. Then i stopped playing for some months (cause that makes it unplayable) and now i reinstalled the game and it's still there. I think in beta i had that problem for a short time but it got away with a patch.
Frequency: always
Platform: PC
PC Manufacturer & Model Number: selfmade. CPU: AMD Phenom II X6
OS: Windows 7 x64
Graphics Card: NVIDIA GeForce GTX 470
ISP: Deutsche Telekom
Type of Internet Connection: A-DSL using wlan. The wlan doesn't work that well sometimes, but in a mmorpg engine choppy internet shouldn't hurt the GUI.