What is www.phpbenchmarks.com ?
You will find lot of benchmarks for PHP frameworks, ORM and libs here.
You can compare results between Apache Bench and Siege, PHP 5.6 to 7.2 and versions of your favorites PHP code.
It's benchmark bundles for almost all Symfony versions.
Symfony 2.0 to 2.3 : use 2.0 version.
Symfony 2.4 to latest : use 1.0 version.
You can find how we benchmark it here.
You can find all Symfony benchmarks here.