Performance issues cont'd

So, continuing the performance issues note from before, here's a post Brad just made on the project wave regarding performance on the Xbox:

I've been incrementally disabling everything trying to isolate the efficiency problem and I found something very surprising. Even disabling most things in drawables manager it's still not smooth. In the dm I disabled add so nothing can be added, I disabled collision detection, and basically everything except the playerShip stuff. I dissabled the background manager, level manager, viewport switcher. No matter what, it's still not smooth. I have no idea where it's hanging up. Player ship maybe? Any ideas?

So... when we have a game that does NOTHING it still doesn't run well. No enemies, no background graphics, just a player ship with a few dozen polygons. This is on the same Xbox 360 that runs Halo 3 and Gears of War and whatnot.

I'm starting to wonder if it's actually possible to make a game run well at all with XNA. I mean, we've pretty much got an NES game level of computation going on here. With everything disabled, it's pretty much on the level of pong.