Right now, there's still a bunch of world-loading/rendering optimization that I need to finish... but if the game is starting to lag after a playing for a while, sometimes just save+quit -> load clears it up for a while.
If the game is running slow right off the bat, then not really sure at this point besides lowering the resolution. Do you know what kind of video card and processor your machine has?
Just for comparison... I do most of my development on an older Thinkpad (Core i5-3320M CPU) - that just has a non-dedicated Intel HD 4000. It runs it more or less okay; not perfect. Does get occasionally sluggish though.