The BrowserNewTabPreloader swaps preloaded docShells into newly created tabs to ensure a smooth tabopen transition. This is of course rather a workaround to make up for missing solutions like generic content preloading or e10s. It would be great if we could get rid of the BrowserNewTabPreloader in favor of something that doesn't involve as much trickery. 1) Creating an nsFrameLoader instance without a document seems impossible. It would be nice to have something ready that we could adopt in nsXULElement::LoadSrc() rather than calling nsFrameLoader::Create(). 2) Assuming about:newtab would work in an OOP browser (which it currently doesn't), how about always loading about:newtab for new tabs in a remote=true browser? As soon as a new URL is entered or one of the tiles is clicked we can remove and re-insert the browser to create a new non-remote frame loader, like updateBrowserRemoteness() does. 3) Having pre-rendering functionality would be nice, esp. in combination with our speculative connect framework. Alas, it doesn't seem like there is any interest in bug 730101 anytime soon. 4) Any other ideas?

Investigation done. I'll file a new bug with an explicit proposal and patch.