Making Programs Faster

`Devel::DProf`

To analyze the tmon.out file, you run dprofpp
It gets a lot of options to control the format of the report it generates
By default it looks like this:

     Total Elapsed Time = 7.592672 Seconds
       User+System Time = 7.122672 Seconds
     Exclusive Times
     %Time ExclSec CumulS #Calls sec/call Csec/c  Name
      30.1   2.149  2.125   4104   0.0005 0.0005  Mail::Header::_fold_line
      24.6   1.756  3.414   2052   0.0009 0.0017  Mail::Header::_fmt_line
      12.2   0.870  0.869    109   0.0080 0.0080  main::letter_histogram
      6.60   0.470  0.458   2052   0.0002 0.0002  Mail::Header::_insert
      5.77   0.411  4.275    109   0.0038 0.0392  Mail::Header::extract
      5.34   0.380  0.367   2161   0.0002 0.0002  Mail::Header::_tag_case
      5.34   0.380  0.358   3604   0.0001 0.0001  Mail::Header::fold_length
      3.72   0.265  1.377    109   0.0024 0.0126  Mail::Header::fold
      2.39   0.170  0.170      1   0.1700 0.1700  Mail::Util::read_mbox
      1.40   0.100  5.917    116   0.0009 0.0510  Mail::Internet::BEGIN
      1.40   0.100  0.269      4   0.0250 0.0674  main::BEGIN
      0.70   0.050  0.048    327   0.0002 0.0001  Mail::Internet::body
      0.70   0.050  5.700    109   0.0005 0.0523  Mail::Header::header
      0.56   0.040  0.091    218   0.0002 0.0004  Mail::Internet::as_string
      0.42   0.030  0.030      1   0.0300 0.0300  warnings::BEGIN

This lists the 15 subroutines that consumed the most total CPU time
The top 5 account for 80% of the program's run time