Hmmm. I finally got around to setting up static GZip compression on my server. I can't remember the reason why I didn't do this sooner, but today I was looking at some of my CSS files getting out of hand so I thought I better check into this again.

It's easy enough to do. MVP Omar Al Zabir has a nice post that summarizes how to set up IIS 6 for GZip compression which is quickly done by changing a few settings in Metabase.xml. IIS 6 basically writes out the content as compressed files to a sort of cache folder and then serves the compressed data directly from there (which incidentally might be a good approach for serving GZip content from ASP.NET more efficiently as well if you can cache the data).

Anyway it works without any fanfare, except it seems that none of the CSS content in any App_Themes folders are compression. Doing a quick search on App_Themes and IIS 6 compression turns up nothing.

On my site try the WebLog or the Web Store (checking with Fiddler or FireBug) both of which have App_Themes hosted CSS and both of which are not compressing. Yet on the home page the site style sheet (westwind.css) properly encodes.

It looks like there's something in the App_Themes folder foiling the compression (perhaps the long path name or the _). Here's what my compressed files folder looks like:

You can see all the files that have been compressed here. Notice there are NO App_Themes folder anywhere although there's about 10 ASP.NET apps running on my server.

Could anybody verify this behavior with their IIS 6 server by any chance?If you're running IIS 6 with static GZip compression can you check and see if App_Themes css files are getting compressed?