<head> tags underneath <body> tags. Why do this? One reason is to make cache instructions work better, as described by Microsoft here.Another is described in High Performance Web Sites: Rule 6 – Move Scripts to the Bottom by Steve Souders, Yahoo!'s Chief Performance Yahoo!
With stylesheets, progressive rendering is blocked until all stylesheets have been downloaded. That’s why it’s best to move stylesheets to the document HEAD, so they get downloaded first and rendering isn’t blocked. With scripts, progressive rendering is blocked for all content below the script. Moving scripts as low in the page as possible means there's more content above the script that is rendered sooner.
The second problem caused by scripts is blocking parallel downloads.
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