I'm experimenting with Chrome rel="prerender". On one specific site, the page I'm suggesting gets prerendered, but is then loaded again, not switched when the link is clicked. As reported on chrome://net-internals/#prerender, the reason for failing is listed as Non-Empty Browsing Instance.
I've tried searching for some explanation about this particular problem, but haven't found any. Does anyone have any experience or ideas what causes Non-Empty Browsing Instance, and how to fix it?