the way this feature worked was to present screenshot of a start page, while waiting for the actual start page content to load. It worked well in case of fast compter where the color flash was annoying but short. But in the case of slow or heavily loaded machine it resulted in "seeing startpage but not being able to perform any actions" - thus very bad user experience. The advantage of the feature we are introducing Today, is loading startpage and making it usable instantly even on slow or heavily loaded machine.
About navigating out of the start page:
we are definitely thinking about options here. To understand it, let me try to explain why the flash appears in the first place. In nutshell, this is how chromium works, navigation means switching to new render process for the page we are trying to load. Until the new renderer produces first picture, some static color is shown. There are different strategies for picking which color to show, but in the described case background color of the previous page / start page is shown. As first option, we can keep showing start page until new page loads, but this requires careful UX design as slow page load could be mistaken with start page slowly reacting to clicking on the tile. As second option we can show theme color instead of start page average background color as we do Today. This is what other browsers do and it doesn't look that bad.