Can you run it without the tweak or do you really really need it? Because that's what the problem is and I don't think there's a way around it.
Please, ensure you have your Frame Limit set to 60 or LESS and that your monitor's Refresh Rate is 60 Hz. Allowing the game to render / or draw more than 60 FPS can introduce these types of physics issues. Alternatively, try running the game on one card if using SLI / Crossfire and see if that stops it.
(Multiple GPUs have proven to be problematic with the game in the past. Since the physics engine relies on accurate frame-timing, when two GPUs "split" the frame, the engine may not be able to accurately target the frame to update the physics...or it may apply a value to both, resulting in constantly fluctuating physics values that make the hair "vibrate".)
(Multiple GPUs have proven to be problematic with the game in the past. Since the physics engine relies on accurate frame-timing, when two GPUs "split" the frame, the engine may not be able to accurately target the frame to update the physics...or it may apply a value to both, resulting in constantly fluctuating physics values that make the hair "vibrate".)