Well phpVMS is written on Codon, I used to have that in active development for an old job. It's based on CakePHP (well, not initially, but I've modified it). It's really lightweight. But now, vaCentral is written using CakePHP. I use a custom "framework" for the API server (it's a MVC format in 3 files), super lightweight.
I am a big fan of Cake, there's alot of Ruby-isms. I'm looking out for symfony2, and the next version of Cake. CodeIgniter is ok to start with, but there's no ORM. I like recess too. But Cake is my "goto" framework, it's great all around. It's benchmarked to be slower, but with some caching, it runs just fine. In my benchmarks, all the frameworks ran about the same, since it's server-limited before you even hit code maximums IMO.