Benchmarking

[eluser]WanWizard[/eluser]
Total execution time = from when the Benchmark library is loaded until the profiler fetches the result
Loading time base classes = from when the Benchmark library is loaded until your requested controller is loaded
Controller execution time = from before the controller method is called (but after the pre_controller hook), until after the post_controller hook is finished.

Check the CI code if you want to know how it works internally ( in this case, ./system/codeigniter/Codeigniter.php ).