This chart shows the number of requests per second that were performed (more is better). You can see that PHP 7 can do a lot more in comparison with the other versions. Response times drop from 0.2269 to 0.0865 seconds in the production environment.

http://www.intracto.com/nl/blog/running-symfony2-on-php7

Nice benchmark-work by Tom Van Looy. It is clear that you'll benefit from impressive speed bumps when upgrading to the next major version of PHP. Tom also provides instructions on how to setup PHP7 so you can perform your own tests.