If you're looking for a good php framework, I highly recommend you look at http://codeigniter.com. Just spend half an hour on the user guide and I promise you that you will be hooked! It makes general things so easy that you will probably never look back at pure php again for a site.
Cake is decent. Zend Framework too. Most of my work is done using OpenSeeds, which is a framework that my company is currently developing. We've made it tight enough where you can build a fully functional class that can take form input, validate it, and read/write from the database in - just in a couple of minutes. We'll be releasing a much needed update publically in a couple of weeks, so I wouldn't bother downloading the old version right now. You can take a look at the docs, though, to get an idea of how it works.
I believe Zend is great but a heavy weight when it comes to frameworks. I like to keep it as simply as possible so I will be looking into CakePHP to check performance.