PHP5 adds a bit to its error model, plus adds a completely new model for exceptions.
From The Blog
PHP5 only has a few new functions relating to graphics, but they’re useful ones.
PHP5 has added some new interfaces for MySQL.
PHP5 introduces limited type hinting.
I’ve noticed that some of sites I visit are slow to load. There might not be a lot of images or content on the page, but the page seems to lag for a few seconds before it begins displaying in my browser. Why is this?