1. Can you please download and run this diagnostic? http://blendogames.com/dev/3dtest.zip
Let me know if it runs at a smooth framerate.
2. What video card does your laptop have?
3. Can you please try running the game with these command-line parameters:
C:\program files (x86)\steam\steamapps\common\atomzombiesmasher\data\atomzombiesmasher.exe -sound 0 -joystick 0 -vsync 0 -fullscreen 1
4. Try going into the options menu and disabling the VSync option.