It was on an external HDD, but I just tried it on a regular SATA connection and it works just fine. First time I ever had any issues with the external, so I guess the USB connection is at fault. In any case, consider it fixed unless others have the same issue, of course.
I started with v0.11 Windows to try out the game but it runs terribly (input lag and abhorrent framerate). So I tried v0.1 and the game runs smoothly. I'm running Windows 10 but I just can't figure out why v0.11 runs so poorly on my rig.