I have an RX580 8gb and since the Nov 8th update this game has been unplayable with micro-stutter. I just used my Radeon settings to override the game settings and so far (only one game) no stuttering. This may not be true for all maps. Time will tell, but for now it seems the problem is internal to Sandstorms GPU settings.
I have disabled all in game graphics with my Radeon settings. I than launch the game from Radeon and this has helped me a bunch. It seems to degrade over time but a game relaunch, again from Radeon, seems to fix it. I still run it on low, but get FPS as high as 130. I am no developer, but this tells me the issue is in the games graphic settings.