25.4. Optimization

Always be careful with optimization. The hacks in this section are all micro-optimizations. They make a small segment of your code faster, at the expense of some readability. The vast majority of the time, applying these will give no benefit to users of your code. Before using any of these, make sure you run a profiler over your code and identify the bottlenecks.

On OS X, there are several tools that you can use for profiling an application. Shark and Sampler are the two that have been around for a while, but XCode 3 introduced a new one. The Instruments application is built on Sun’s DTrace framework, included with Leopard and newer releases of OS X. DTrace allows running applications to be instrumented and profiled in a wide variety of ways. Figure 25.1 shows the CPU sampler attached to TextEdit.