I think you're confusing layout with rendering. The DOM's elements are all in memory, along with their layout coordinates. What tile(s) the browser needs to render is a fast binary search combined with simple math. Rendering and zooming tiles isn't free, but let's not get dramatic. Also, if there isn't anything animating, once rendered, each tiles pixels are less than a MB (800x480x2). Have you ever used a Nokia tablet or an iPhone OS device with only 128MB of RAM? They work just fine: The Nokias have fast scrolling scroll bars and the iPhone OS devices let you click on the status bar to jump to the top of the screen. This is no big deal and it's one simple function call. Trust me, I know, I've called it on all devices mentioned. I think the n900 can handle it.