Hi, I'm currently working on a Space Invaders, and I have an issue. When a laser is fired, <a href="http://docs.racket-lang.org/gui/bitmap-dc_.html?q=get-pixel#%28meth._%28%28%28lib._mred/main..rkt%29._bitmap-dc%7E25%29._get-pixel%29%29">get-pixel</a> uses its coordinates to send the color of the pixel at these coordinates to a color% object at every tick. Since the background is black and that the invaders are white, when (> (send my-color-object blue) 0 ) (which gives the 0-255 blue value) , my program starts to look for a dead flagged invader and removes it from the list. An invader is considered as dead when a laser enters its perimeter. However, it seems get-pixel is very slow when called at every tick. When you fire 2 lasers, it becomes unplayable. And of course, calling it every 2 ticks or more is not efficient enough. Feel free to give me your thoughts on this... Thanks.