Profiling Viewer opens and visualizes callgrind files. You can use Treemap, Callgraph, flat or hierarchic lists to identify functions where your application spends more time than expected. You can see how many times a function was called and what function made the call. This information may help you to optimize and improve your code. The required callgrind profiling data can be generated with various external tools available for many platforms and programing languages. For example you can open files generated by Valgrind, ruby-prof, the Xdebug extension for PHP, Python cProfile with pyprof2calltree and many other profiling tools with callgrind file output.