On his site today Lukasz Kujawa has a post that compares some performance benchmarks of several popular PHP frameworks including Slim, CodeIgniter, Laravel, Symfony2 and Zend Framework 2.
There are many assumptions around performance of different PHP frameworks. I frequently hear strong opinions about superiority X over Y in this context. There are companies writing new PHP frameworks from scratch because available solutions are too slow for them. What does it really mean? Does the framework performance matters? Before answering this questions lets check how slow is your framework!
He took the "quick start" projects provided for each of the examples and ran some tests with the Apache Benchmark (ab) tool against EC2 instances, all configured the same way. The results weren't overly surprising with Slim beating the others hands down (it's a micro-framework after all) and Kohana and CodeIgniter coming in second and third. The frameworks with more overhead like Zend Framework and Symfony ranked some of the slowest.