Slim group performance test

Setup

1. After cloning the repo, run composer install
2. Add the nginx.conf file to your nginx config
3. Compare the performance of the following routes:
   1. http://localhost:8080/all/group1/sub1/123
   2. http://localhost:8080/single/group1/sub1/123

Ideally the performance would be about the same for both routes, but currently (Slim 3.8.1) the first route is many times slower.

The reason for this is that Slim currently runs all the code to generate routes inside group and subgroup callbacks, even if the group/subgroup does not contain the route being navigated to.