Paul Jones has information in this new post on his blog with a how-to on doing some benchmarking inside of the Solar application framework.
Comparative benchmarking is tedious work. It's not hard to do, it's just no fun to set up the same scaffold every time you want to figure out how long it takes different pieces of code to execute.
To do a benchmark, essentially you need only four things: a timing mechanism, a loop to run the first case, a loop to run the second case, and a way to show the time taken by each loop.
To illustrate, he gives example code of a simple loop and the output of its timing results. But, since this is a boring example, he demonstrates something a bit more complex - something using Solar_Test_Bench and Solar_Test. The example of using these two components pits require_once and Solar's own loadClass against each other. He also includes another similar test, one comparing fopen and exploding the include path to check for a file's existence.