On Byster.net today, there's this new post detailing some benchmarks they've done with some of the functionality in PHP5.

Included in the list of tests were:

• Reading an integer array
• Parsing variable names
• Splitting out text
• working with a random number generator.

For each of the tests, they have a few different methods of doing the same thing and the results (in milliseconds) plotted out in bar graphs. Some of the results are surprising, but most are expected (if you work with optimizing PHP much at all). It's a good amount of coverage of functionality, though - most aspects of everyday programming are here.