The Adminxweb site has put together some framework benchmarks for several of the popular frameworks out there, some of which you may not have heard of before.

There are various PHP frameworks and they all have different speeds. The only way to judge a framework by its speed is by benchmarking - conducting tests and comparing the results. [...] Comparing various benchmarks is less of a scientific comparison and more of a subjective application. So in this post, I will review the performance of these frameworks according to the same metrics. This will allow us to arrive at the closest thing there is to an objective winner.

Among the ones they profiled, the DooPHP framework was the only one that came up with a 10 of 10 rating based on speed. It's compared to other frameworks like CodeIgniter, symfony, Solar and the Zend Framework. Take the findings with a grain of salt, however - the author doesn't provide the methods she used to arrive at the numbers. If you would like something with a bit more substance, check out Paul Jones' framework benchmarking tool posted on github.