Although you mention DProf as your profiler of choice, I've also liked running
Apache::SmallProf which allows the hooks from
Devel::SmallProf into mod_perl. In any event, both SmallProf and DProf are really handy tools for mod_perl based applications.
Good luck!
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perl -le '$.=[qw(104 97 124 124 116 97)];*p=sub{[@{$_[0]},(45)x 2]};*d=sub{[(45)x 2,@{$_[0]}]};print map{chr}@{p(d($.))}'