I gave it another go and it's been a lot better today, still getting the occasional audio dropout, but mostly OK. It was extremely hot yesterday, so I wonder if the Steam Machine was underclocking itself to keep cool.

Hi, I just got a Steam Machine and controller today, set it up and downloaded Factorio. Saw there was a developer suggested controller binding, so thought it would be good.
I loaded the game, massive lag, audio dropouts on the main menu. I closed the game and switched to compatibility mode and tried ...