Please keep in mind that this an English support channel.
Sounds like you are having some issues with the camera becoming jerky during aiming?
You stated that you tried to play in windowed mode. Is this before/after you started experiencing this? Also, can you please post your DxDiag so that I can further review your system specs?
Well I'll try it in english even if I am not that good at it^^
I experienced this lag since my very first game on pc.. Ist not only when aiming, it feels like every 2-3 sec there is a framedrop, it doesnt matter if I am walking or shooting or doing anything else. Also these lags are worse and better from game to game. E.g. in the first game there is almost no lag and in the next I can barely move/aim/shoot.
I dont really know which information are important but here is my DxDiag:
Windows 7 Home Premium 64-Bit-Version (6.1 Build 7601)
Bios: Award Modular BIOS v6.00PG
Processor: AMD FX(tm)-8350 Eight-Core Processor (8CPUs), ~4GHz
NVIDIA GeFroce GTX 680, DAC-Typ: Integrated RAMDAC, 4039MB
Monitor: PNP-Monitor (Standard)
Hope that's enough.