I have 17 live folders on my 920, no more lag than it ever had, even fresh out of the box on 8.0. Best trick with live folders: Any non-live tiles in any folder should be set to the small size so they don't cycle in the folder, reducing the load. Also, small tile live folders don't cycle at all, so no load from them. And finally, if there's nothing on a live tile that you care about seeing, either shut off the updates or make it a small tile, whether it's in a folder or not. I'll grant that my start screen isn't a thing of great beauty (I don't bother with a background image, either), but it's fast and functional, and everything I use is at my fingertips. As a computer programmer for 3 decades and an engineer before that, that's what I care about.