I benchmarked “quick start” projects. That gives some idea on what is the base line for every framework and makes it possible to reproduce my tests (and argue against them).
Code was hosted on Amazon EC2 medium instance. I installed PHP-APC to avoid disc access and code parsing. I also made sure there is no I/O on Apache2 or application level. I set logs and cache paths to “/dev/shm/”. I tweaked projects to make them return roughly the same amount of data (10KB). All virtual hosts had the same mod_rewrite rules. AllowOveride was set to None.

Benchmarked frameworks:

• Cake PHP
• Code Igniter
• Fuel PHP
• Hazaar MVC
• Kohana
• Laravel
• Netter
• Phalcon
• Silex
• Slim Framework
• Symfony 2
• YII
• Zend Framework 1
• Zend Framework 2

Requests per second from Apache Benchamrk with c=20 and n=500.

I’m not surprised, Slim is the fastest because it’s a micro framework. The Quick Start project didn’t use any templates or layout which obviously contributed to the reading.
Zend1 is twice faster than Symfony2 and Zend2 but in my experience the number will quickly go down in a real live setup.

Frameworks should speed up development, performance is a secondary concern. Zend 2 and Symfony2 could do better but it’s not bad. There are ways to improve those numbers on production servers. Don’t reinvent the wheel, learn and use frameworks. There are various options which balance between performance and features.

ps. If you have space for more I would like to recommend you great research on performance of web frameworks by techempower.

ps2. Thank you for your suggestion Ron. Phalcon is the new winner.