I'm pretty sure it just left early access so the small discount makes sense. It's a stellar game and honestly much longer than you'd think with a game that screams casual.
I force most games into 45 or 60 of I can help it. I've never noticed bad performance while swimming so I loaded it up and played for a bit. I was locked to 60 with no issues. Definitely fixed whatever performance issues they had.
FYI, if you’re seeming the mathematical balance between 30 and 60 fps, 40 is what you’re looking for. By frame-time, 40 is exactly between 30 and 60 (25ms vs 16.67 and 33.33, respectively).