Create a seperate vhost for tools and applications.

Let's create a vhost for things other than Drupal / application development (XHProf, Webgrind, PHPMyAdmin, etc).

Something like vagrant.vbox.local, then webgrind would be at vagrant.vbox.local/webgrind.

Alternatively, we could use a port, so dev-site.vbox.local:8000/webgrind, that would have the additional side-effect of bypassing varnish.