Program Repair Shop
The big loop

     391      if ($filesz > 1024)
     392      {
     393        my (@name_list) = compare_by_first_block (1024,
     394                @{$names_by_size{$filesz}});
     395  
     423        if ($num_files_this_size > 20)
     424        {
     425            for $array_ref (@name_list)
     426            {
     427                compare_by_md5_sum (@$array_ref);  # results in @md5_LoL
     428            }
     429        }
     430        else
     431        {
     432            @md5_LoL = @name_list;  # skip md5 sum step
     433        }
     434  
     441        while ($array_ref = shift (@md5_LoL))
     442        {
     445            compare_by_fc (@$array_ref);  # results in @fc_LoL
     446        }
     447      }
     448      else
     449      {
     450        # For files small enough to be read entirely into RAM,
     451        # handle them directly on one pass!
     452  
     453        @fc_LoL = compare_by_first_block ($filesz, @{$names_by_size{$filesz}});
     454      }