The Perl 5 module Devel::NYTProf is a powerful feature-rich perl source code profiler. - Performs per-line statement profiling for fine detail - Performs per-subroutine statement profiling for overview - Performs per-block statement profiling (the first profiler to do so) - Accounts correctly for time spent after calls return - Performs inclusive and exclusive timing of subroutines - Subroutine times are per calling location (a powerful feature) - Can profile compile-time activity, just run-time, or just END time - Uses novel techniques for efficient profiling - Sub-microsecond (100ns) resolution on systems with clock_gettime() - Very fast - the fastest statement and subroutine profilers for perl - Handles applications that fork, with no performance cost - Immune from noise caused by profiling overheads and I/O - Program being profiled can stop/start the profiler - Generates richly annotated and cross-linked html reports - Trivial to use with mod_perl - add one line to httpd.conf - Includes an extensive test suite - Tested on very large codebases NyTProf is effectively two profilers in one: a statement profiler, and a subroutine profiler.