The 90-10 Rule In Action

Counting modules, the program has 2,848 lines of code
- (I didn't count whitespace, comments, POD, lines with just braces, etc.)

     Subroutine            %time   cum.   lines   cum.  cum%

     M::H::_fold_line       30.1   30.1      48     48   1.7   
     M::H::_fmt_line        24.6   54.7      34     82   2.9   
     letter_histogram       12.2   66.9       3     85   3.0      
     M::H::_insert           6.6   73.5      22    107   3.8      
     M::H::extract           5.8   79.3      16    123   4.3      
     M::H::_tag_case         5.3   82.6       6    129   4.5   
     M::H::fold_length       5.3   87.9      15    144   5.1      
     M::H::fold              3.7   91.6      13    157   5.5      
     M::U::read_mbox         2.4   94.0      21    178   6.3      
     M::I::BEGIN             1.4   95.4      18    196   6.9      
     ...

7% of the code accounts for more than 95% of the run time
- 5% of the code accounts for more than 80% of the run time