Technically, even if you render outside the visible area you still incur reflows/repaints. A fragment isn't rendered at all, but lets you build the entire collection as HTML once then do just one reflow/repaint to add the whole fragment to the DOM.

What about using something like jquery detach? Then you could, when rendering, detach the element, render all the content, subviews, and re-append it. That shouldn't trigger reflows, right?

Correct. So far as I know, the way jQuery detach works is to remove it from the DOM and then return the individual element. The element could act as a fragment, because it can contain children, and then be reappended to the DOM.

Right, and even better than a document fragment since fragments have both unusual semantics and API limitations that normal elements do not (e.g., no getElementsByTagName or getElementById).

This --^

Great answer!