Why does this cycle kill the performance of a simple Marmalade Quick app?

Question

local board=director:createSprite(0,200);

for y = 0, w*15, w do
  for x = 0, w*15, w do
    local space = director:createRectangle({x=x, y=y, w=w-1, h=w-1, strokeWidth=0, color=color.grey})

    board:addChild(space)
  end
end

In addition to the above, I have some tiles that should be easily moved.

I was struck by performance degradation by adding these 225 static objects to the set designer ... I was hoping for better performance than this. Am I missing something? Is there any other approach I should try? Or is Marmalade Fast just not that fast?