Page Speed: Serve static content from a cookieless domain

Page Speed recommends:

Enable proxy caching

For resources that rarely change, set caching headers for browsers and proxies. Because cookies will not be sent for these resources, there is no risk that proxy caches will cache user-specific content.

Don't serve early loaded external JS files from the cookieless domain

For JavaScript referenced in the head of the document and needed for page startup, it should be served from the same hostname as the main document. Because most browsers block other downloads and rendering until all JavaScript files have been downloaded, parsed and executed, it's better to avoid the risk of an additional DNS lookup at this point of processing.

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