Disable OutputCaching in MVC3 when running in DEBUG or under Debugger?

The web.config.debug file is used only when you build a deployment package. If you run your site locally in Cassini for example it is completely ignored. So you may try disabling cache in your web.config:

<system.web>
    <caching>
        <outputCache enableOutputCache="false" />
    </caching>
</system.web>

and in your web.config.release enable the cache. Note though that if you don't use the web deployment package feature those files are completely ignored.