For whatever reason, this game (so far--18 levels complete) has not been causing me lag issues. And my laptop has those issues a lot.... I have no idea why.
Also, found an epic glitch. It is best done after you complete the game. 1) Sell all your stuff. 2) Buy a single gun; DO NOT PLACE IT! 3) Hit "Back." 4) If you want, get the "Good Ending" to erase all your money. However, after completing this glitch, if you do this, you will have to restart to get any money back. 5) Play game. Your gun will be way below the bottom of the screen on the left-hand side. Glitch.