Stutters, hiccups , framedrops i found the cause!! Edit***

Ok after some testing the problem for me shows like this:

Pressing button 1 on the keyboard repeatedly does nothing ,its fine.
If i spam 2, or 3 its giving the game an interrupt. Result-> stuttering

Switching weapons via mouse wheel does not exhibit this issue, its fine.

So whatever this game is doing, there's something broken.