Weird performance issue (stuttering) due to keyboard

[john2gr]

Now here is a weird issue with the keyboard.

While pressing any button (W-A-S-D) i get stuttering and the framerate drops a bit. You can easily notice it while not moving the mouse as the screen stutters. I wondered why i could notice such thing (as the performance is great in my machine), so i decided to plug my gamepad.

Here is the interesting part. While moving my character with the gamepad there wasn't any stuttering. Everything was smooth.

The point is that i don't want to use a gamepad, this is an FPS for crying out loud.

As i'm not getting this stuttering thing in any other of my games, i'm pretty sure that there is a major bug with the keyboard in ArmA2. FYI, i've renamed the exe file to "crysis64.exe" to get SLI and below are my specs with the settings and the benchmark results.

Intel Core2Duo E6600 @ 3.51Ghz
3GB DDR2
EVGA GTX295

1920x1440 with Very High settings (except High in terrain): 50fps average in the benchmark.