PHP Quick Profiler: Analyzing PHP Performance
Firebug is the most popular tool for analyzing HTML, CSS & JavaScript based webpages. Now, there is PHP Quick Profiler (PQP), which can be called as Firebug for PHP.

It is specially focused on analyzing the performance of PHP codes. With a beautiful interface, PQP can:
* log memory usage
* display the number & sizes of included files
* show page execution times
* log database queries
PHP Quick Profiler is not a plug & play solution as every project may have a totally different structure. But, by following the setup information & the example provided, it is easy to integrate.
To see how functional it is, you can check the demo.
for more information, you can check here.