Problem Analysis
While doing some front-end performance enhancements on a project that utilized extensive javascript and flash, I found that IE6 doesn’t like it when you compress text/xml with mod_deflate/mod_gzip. From a user perspective, the Flash component would show, but any XML data being transferred to the Flash component will be rejected–you get a blank canvas/UI without any data/Preloader will show. Incidentally, Internet Explorer 7, Firefox 2+, Safari all handle gzipped text/xml without a problem.
Final Solution
Only apply gzip to the following content types: text/plain, text/html, text/javascript, and text/css–Do not apply it to text/xml if your Flash components use XML data sets from the back-end.
This solution gzips all your assets (Javascript and CSS), without breaking Flash components in your web application.
Further Reading
mod_deflate tutorial - http://www.howtoforge.com/apache2_mod_deflate
