While I'm hunting around to see how I can improve the bandwidth while I've used WebResource.axd embeded resource files extensively, it seems like the cache-control is always put as "private" which means it never get cached! even in the same page!
That's really a performance penalty.
After using fiddler to find out the fact, still don't have any clue since the AssemblyInfo's WebResource method doesn't give any option to caching customization. Thanks to Google again, I've got to Rick Strahl's WebLog on the issue of webresource.axd caching.
Basically, what happen is that when the library is compiled in debug mode, the caching is private (that means no caching) but while compiled in production mode, it will be public. Thank God, that means my codes will simply get its performance up when I switch over to production compilation.