Google has launched a new beta (1.9) of mod_pagespeed for apache 2. With it pages should increase download time with up to 50%.
From their page:Page Speed Family
The Page Speed family consists of several products. Web developers can use the Page Speed extension for Firefox/Firebug to analyze performance issues while developing web pages. Apache web hosters can use mod_pagespeed, a module for the Apache™ HTTP Server that automatically optimizes web pages and their resources at serving time. For web developers
Analyze with Firefox® and Firebug
The Page Speed extension is the fastest way to get accurate performance analysis of your web pages. It is also our prefered environment for introducing new performance best practices. With the Page Speed extension, you can analyze the performance of your pages and get specific suggestions on how to optimize them. For web hosters
Optimize with Apache™
mod_pagespeed is the latest addition to our family of products, performing on-the-fly optimization in the Apache™ 2 HTTP Server. It provides webmasters and web developers that manage their Apache 2 configuration with technology that applies Page Speed performance best practices automatically. Webmasters can get the benefits of the optimizations without having to manually going back and fixing the performance issues that Page Speed detects.
Have a look here for all the info : http://code.google.com/speed/page-speed/docs/overview.html