I thought I would run this here, as the conventional solutions (disable Steam overlay, run without Steam, etcetera) have been ineffective, or in one case seemed to make it even worse.
Starbound is still in beta, but I really enjoy playing it. I run Cinnamon on Ubuntu 14.04 on a 64-bit linux kernel. I have 3GB of RAM, a 3 GHz processor, and a GeForce GT610 graphics card with 2GB VRAM and external cooling (core temperature never rises above 50°C). All the same, the whole program will bog down to 4-10 FPS, pretty frequently.
The nature of the slowdowns makes me think that it might be an inefficiency in buffering data to the graphics card, or something in the drawing algorithm; but I can't be sure. I have zero interest in running it on Windows. Has anyone resolved this issue for a similar platform, and would you explain how?