XHProf is a function-level hierarchical profiler for PHP and has a simple HTML
based navigational interface. The raw data collection component is implemented
in C (as a PHP extension). The reporting/UI layer is all in PHP. It is capable
of reporting function-level inclusive and exclusive wall times, memory usage,
CPU times and number of calls for each function. Additionally, it supports
ability to compare two runs (hierarchical DIFF reports), or aggregate results
from multiple runs.

WWW: https://pecl.php.net/package/xhprof