If you want a game to be fast, then have it do less work.
elafreat, one idea is to detect what the current FPS (frames per second) is and reduce the number of objects on the screen if the FPS gets too low. Another idea is try to do the least amount of actions on every tick, which one way of doing this would be to use the System."every X seconds" instead.
And then, perhaps not the most fun method, read through the entire C2 manual to learn many new things, and there are some great tutorials with even more tips and tricks.