The Linux Tools Project Function Callgraph plugin aims to provide an easy-to-use tool for C/C++ function and timing visualization.
The Callgraph plugin uses the powerful SystemTap language as a back-end, allowing it to monitor the status of a program -- function
calls, returns, times and even user-space variables. The resulting data is displayed using Zest to create a visually pleasing graph
of your entire program, or whatever parts of it you suggest. The graph shows timing information, and can be used for optimization.
In Aggregate Mode, you can see a grid of all functions used in your program, coloured and sized according to the number of calls and the amount of time taken by each function. If you hold ctrl and double-click on a function, you will be taken to the point in code where that function was defined.