We've started using the DevExpress MVC controls, which requires this code added in our Site.Master:

```
<% Html.DevExpress().RenderScripts(Page,
       new Script { ExtensionSuite = ExtensionSuite.GridView },
       new Script { ExtensionSuite = ExtensionSuite.HtmlEditor },
       new Script { ExtensionSuite = ExtensionSuite.Editors },
       new Script { ExtensionSuite = ExtensionSuite.NavigationAndLayout },
       new Script { ExtensionSuite = ExtensionSuite.Chart },
       new Script { ExtensionSuite = ExtensionSuite.Report }
 ); %>

```

But this renders a massive 2mb javascript file through a handler called DXR.axd. When using Firefox this javascript is too large and increases the page's onload time from ~500 ms to ~5,000 ms (I timed it before and after). 

Using Chrome it loads in ~750ms

This is a severe performance hit and causes a very noticeable pause when the page is rendering. Firefox reports that the DOMContentLoaded event takes 5 seconds to fire (because it takes so long to load and parse that 2mb of javascript)

What can I do to fix this problem?

I note that their own site <http://mvc.devexpress.com> has the exact same problem: if you view source and look for "DXR.axd" then download that file it is even bigger, at 2.6mb, and they also have a very slow onload in Firefox