[wp-hackers] Plugin conflicts with latest version of Jetpack

[Otto]

On Wed, Jan 2, 2013 at 1:06 AM, Mike Schinkel <mike at newclarity.net> wrote:
> If I'm not mistaken the browser still requests the file and the server returns a 304 telling the browser to use the cached version, at least that's what HTTPScoop[1] tells me. Having to check and getting a 304 response isn't the same as never having to issue an HTTP GET request and wait, especially if a site has many CSS and/or JS files to check from many different plugins.

This happens because you either:

a) don't have a proper "Expires:" header being sent with the static content,
b) the expiration has, well... expired, or
c) you manually refreshed or hit F5 or something to that effect when
you were testing your theory. Browsers treat a refresh differently
than normal browsing.

Content that is browser-cached and has an expiration date will not be
re-retrieved, or even checked for last-modified, in a normal browsing
situation... until the content has expired. Refreshing is not a normal
browsing situation, it's an explicit request by the user to get new
data.

Check that you are correctly setting Expires headers for your static
content, and see what happens when you're browsing among pages
normally instead of reloading a page for testing purposes.

-Otto