Slow drawing of objects

programming flash
1

Hi.
I am having this simple problem which I hope some of you can help me with.
I’ve written a small program which detects my mouse movement and draws circles on the x- and y-position of the mouse.

code:

function drawCircle(event:MouseEvent){
    graphics.lineStyle(2, 0, 1);
    
    if(event.buttonDown){
        graphics.beginFill(0x000000, 1);
    } else {
        graphics.beginFill(0xFFFFFF, 1);
    }
    
    graphics.drawCircle(mouseX, mouseY, 40);
    graphics.endFill();
}

stage.addEventListener(MouseEvent.MOUSE_MOVE, drawCircle);

As you can probably see: after drawing a lot of circles the program slows down and the framerate makes the circles be placed with a large gap between them. I would guess that the program draws what is behind the current circle even though the user cannot see it?
Can anyone tell me of a way to get past this? I can’t seem to find a solution.

Thanks for your time.