After thorough optimizations of my website (scoring 95 on google PageSpeed & 96 Yahoo YSLOW) I am puzzled by why the header(s?) take up a relatively long time to load. Is 11 KBytes header information not normal? How should a website in which its slowness is caused by headers, be optimized? Suggestions, tests and tricks for php/htaccess are greatly appreciated in order to find and isolate this issue.
So formulating this as an answer. Take a look at the yahoo tips for speeding up your website. yahoo developer network
mainly take care of caching, cache-control and expiry date headers. This has mainly direct influence on the content not the headers but you never know.
Take a look at this this thread
Again its about caching You should also use gzip or module defalt, but again this influences the contents only