Hi!  This is good feedback, in the recent flurry of adds to the game, I need to step back again to make a pass on the frame rate.  Coincidentally I was just doing some optimization that I want to roll out in a build.  Also, I need to move the graphical quality settings into the in-game menu so you can adjust it there rather than from the main menu.  Thanks for checking it out!

Just for reference, the new version 0.6.61 was just released, and it has some optimizations (still more to do), but equally importantly you can adjust the video quality right there in the game from the ESC settings menu.  See if you can dial the quality to a level where your machine likes it best!

Yeah I'll get some ala carte changes in, the video quality slider was the fastest to get in because it'll take time to restructure my options screen for a long set of toggles.  However unless your card is super-low-end (or if you are trying render at 4K) the issues are probably not graphics related, I've experienced some and I'm workin' on it.