@achmed88 A friend of mine has this problem too, but I think it might've been fixed for him. Try deleting your profile file in AppData/Local/Insurgency. You won't lose anything and it might fix the bug.
For the most part, I'm running Sandstorm without any performance issues, really.
I've had this same issue since the second Alpha, I was on the New World Interactive's live stream and the person running to suggested to randomize your appearance, yet that clearly does nothing. Still waiting for a solution.