CSS aggregation is cached and does not refresh until cache is cleared. Thus, when you make a change to a CSS file it is not evident until you clear the Drupal cache.
One of the biggest factors in front-end performance is reducing the number of requests the browser has to make in a single page load. With non-aggregated CSS files, the browser has to make a separate HTTP request for every single file, which contributes to the overall page load time. It is imperative to front-end performance that you aggregate CSS and JS files in a production environment.
Using a tool like yslow or Firebug's Net tab can give you an idea of how many requests are being made.
Further methods to reduce requests are to aggregate remote JS files locally, and use image sprites on CSS background images to reduce the number of images.
Ancillary to the performance concern is the fact that America's sweetheart, Internet Explorer, refuses to read more than 32 stylesheets (and I *believe* 200 kB of CSS?). I don't particularly mind this bug since it is a firm reminder to always turn on aggregation.
On Mon, Aug 15, 2011 at 9:09 PM,
<tony@tony-mac.com> wrote:
It is defined as "Aggregate and compress CSS files"
Yet the effect was to ignore all the changes I made to the css files! Por que?
Sent on the Sprint® Now Network from my BlackBerry®
-----Original Message-----
Cc: support@drupal.org<support@drupal.org>
Subject: Re: [support] Theme css