Yes - putting on head can measure DOM loading and interactions as quick as they happens. But have performance hit - Webkit (Safari, Chrome, etc) doesn't show ev

Yes - putting on head can measure DOM loading and interactions as quick as they happens. But have performance hit - Webkit (Safari, Chrome, etc) doesn't show even single pixel on screen until they load all resources in head. And another bad news - HTTP partition cache for Safari and Chrome. Putting in body - you can not catch all interactions, but won't stop rendering. Everything is an compromise...