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I found this handy for figuring out which subcomponents were killing my site performance:

In httpd.conf:

PerlSetVar MasonPreamble 'use Time::HiRes qw(gettimeofday tv_interval); my $prof_start_time = [gettimeofday];'
PerlSetVar MasonPostamble 'warn __FILE__ . " executed in " . tv_interval($prof_start_time) . "\n";'

Results in output like this in the apache error log:

/var/www/test/session.mpl executed in 0.046672
/var/www/test/autohandler executed in 0.00034

-- AneelNazareth