One of the XNA program managers Michael Klucher explains the performance differences between the Zunes:
http://klucher.com/archive/2008/06/2...-8-and-80.aspx
I've opened up a Connect suggestion for an option to temporarily disable these features. If you want to see an option go in for allowing this, please register and vote on the issue here:
https://connect.microsoft.com/feedba...193&SiteID=226