I have a post regarding on one PHP framework which I am tracing the progress: Yii PHP Framework. I have some updated resources about PHP Frameworks:
It has only simple briefings and personal comments on each of 16 Frameworks, no deep analysis but still worth a look.
A pretty good and neutral reference, it is a dedicated users-driven website for PHP Frameworks. It provides a feature listing chart to compare, a review system for people to post their comments and rankings. By the way the Hottest Framework is CodeIgniter and Yii Framework is #1 in its ranking system. I am pretty sure I will be using Yii for my next start-up project.
These 4 bloggers each provides a self performance testing result for their target Framework. Read their articles and reviews if you don’t want to re-invent the wheel. It can gives you a simple idea about frameworks’ performance and overheads such as memory usage.