You can’t use wildcards in the hosts file either in Linux or Windows, but you can set up a real domain that points to 127.0.0.1 for example here is one that is already set up http://lvh.me this url points to 127.0.0.1 and all you need to do is get your server configuration file to handle lvh.me as the domain for your apps. Now any subdomain of lvh.me will go to your machine when you are testing and you can use urlrewriting to handle the subdomains differently or use routes in rails or a url config in django.
A 230 line patch to the Linux kernel now enables improved response times and great latency reductions.
The patch is called sched_autogroup_enabled and here are some youtube demos from phoronix to back this up.
Here are the two tests, the top one being the patch switched on.