Use Native Methods

When processing strings, don't hesitate to use specialty methods like String.indexOf(), String.lastIndexOf(), and their cousins. These are typically implemented in C/C++ code that easily runs 10-100x faster than doing the same thing in a Java loop.

The flip side of that advice is that punching through to a native method is more expensive than calling an interpreted method. Don't use native methods for trivial computation, if you can avoid it.