Turn off HTTP compression from web.config

<system.webServer>
  <urlCompression doStaticCompression="false" doDynamicCompression="false"/>
</system.webServer>

Related posts:

• Enable caching from ASP.NET (in IIS7)
• A smarter way to include javascripts and CSS to reduce page load times
• A Smarter Way to Include JavaScripts and CSS to Reduce Page Load Times
• ASP.NET: Client side validation don't work in Firefox (and solution)
• Calling methods in an ASP.NET page using jQuery