Clarification from another person experiencing the same issue: a lot of the time the low fps issues persist even after closing the ship designer, forcing a save+reload to get rid of them.
Some more information I found: this issue seems to only happen with DXVK and nvidia GPU's. People using AMD GPU's report seeing no such issues, and in my testing, using proton-ge's PROTON_USE_WINED3D argument to avoid using dxvk makes the game significantly less laggy (but adds a lot of instability issues, so it's not a proper solution).
It seems like it might be a bug with the game itself. See more here: https://github.com/doitsujin/dxvk/issues/2990
I've been getting a freeze and then crash to desktop when looking around bodies that are not earth
GPU: RX 6700XT
Driver/LLVM version: kernel amdgpu module / llvm 12.0.0
Kernel version: 5.15.0-46-generic
Link to full system information report as Gist: sysinfo
Proton version: 7.0-4
game freezes with no response from keyboard or mouse clicks
game crashes to desktop after ~30 seconds
pan camera around any space body
I've had this happen to me on mars, a Kuiper belt object, and an asteroid in the asteroid belt
Try reducing your texture settings. The game is known to load excessive amounts of textures, overwhelming VRAM.
Compatibility Report
System Information
I confirm:
steam-1176470.log.tar.gz
Symptoms
Frame rate drops to below 1 fps on the ship designer screen. Rest of the game runs fine.
Reproduction