It loads for me, however you're right - it takes a LONG time. Much longer than should really be required for a map that simple.
I think the problem boils down to the fact that you have a bunch of asteroids clustered very very very close together.
Consider these lines:
a = AddAsteroid(i*100, 0)
Where i is a value between 0 and 20.
You will therefore end up with 21 asteroids... the first one will be at 0,0. The second will be at 100,0. The third will be at 200,0, and so on.
Each asteroid has a radius of 50. That means it has a diameter of 100. That means all the asteroids are so close together that they are actually touching!
Also, the game seems to want to make the player's asteroid larger than all the others. So what happens is that a bunch of the nearby asteroids are actually inside the player's asteroid.
I think that the closer-togetherness of the asteroids, and the asteroids-inside-asteroids, is what is causing the slowness. I don't know why it happens exactly, but from my experiments it seems that is the common denominator here.
I changed those lines as follows:
a = AddAsteroid(i*700, 0)
...and it loads in a snap. :>
Hope this helps you Orion. Let us know how you get on - it's always cool to see new designers joining! :>