Code tuning is an essential part of programming. But most programmers would rather try to complete the project in hand then spend time optimizing a piece of code. A well tuned and optimized code block can speedup your application by an order of magnitude or even more.
Many people confuse profiling with benchmarking. A profiler is a analysis tool that lets you measure the performance of code at runtime. Profiling an application lets you find bottlenecks in your application code. You can find which part of your code is taking most of the time, you can than optimize that part of code. For example if there are 4 functions in your application, profiling may report the following distribution: