One thing I've noticed about CloudFlare and Google's web servers are that they both use lowercase response headers. Is this just for looks, or does it actually provide a performance increase? I'm considering doing it for my custom nginx build, but as of now, I am not exactly sure if there will be any negative/positive consequences. I am aware that the RFC 2616 spec on HTTP 1.1 says that headers are case insensitive, so I am sure that it wouldn't cause any issues otherwise Google and CloudFlare wouldn't be using them.
Example response headers from google.com:
HTTP/1.1 200 OK status: 200 OK version: HTTP/1.1 cache-control: private, max-age=0 content-encoding: gzip content-type: text/html; charset=UTF-8 date: Tue, 22 Jan 2013 20:58:07 GMT expires: -1 server: gws x-frame-options: SAMEORIGIN x-xss-protection: 1; mode=block