@ex32 For the first issue, yes, the debugger sucks for checking performance. I recommend you only use it for checking specific stats, like collision checks for example. If you want a more in-depth debugger, that doesn't slow your game down, then try the one that comes with Internet Explorer. Just press F12 and go to the debugger tab.
As for the "2000 collision checks" you'll need to upload a .capx before we can really say what is going on. That's seems excessively high.