Good talk about clarifying how composer works, Jordi's way :)
Even if you have already used composer, this talk would be a good one to attend.
Fair overview of PHP 5.5 new features. I missed a deeper look at benefits and contexts in which these could (or should) be used.
Brilliant talk. I was familiar with many of the topics introduced, yet Lorenzo managed both to open up new perspectives and entertain me. A great talk by a great engineer!
Good talk on how PHP uses memory. A bit of devops hints here and there.
Good explanation of internal processes for getting and releleasing memory. Best suggestion for batch operation and debugging I'm taking home: xdebug_debug_zval function and how class attributes are treated.