The implementation of these functions in darcs is from 2008.
With this patch we trim some lines of code and have a small memory
improvement, here on patch index creation in the darcs.net repo:

before:
        total time  =        5.95 secs   (5945 ticks @ 1000 us, 1 processor)
        total alloc = 4,126,233,968 bytes  (excludes profiling overheads)

after (two measurings):
        total time  =        5.85 secs   (5853 ticks @ 1000 us, 1 processor)
        total alloc = 3,892,040,296 bytes  (excludes profiling overheads)

        total time  =        5.97 secs   (5969 ticks @ 1000 us, 1 processor)
        total alloc = 3,892,020,360 bytes  (excludes profiling overheads)

1 patch for repository http://darcs.net:

patch 0e0682af43f03b9e3299ecee959596b7e80d0c3b
Author: Guillaume Hoffmann <guillaumh@gmail.com>
Date:   Wed Nov 12 15:45:34 ART 2014
  * use bytestring functions dropWhile and break instead of ours

Attachments

• patch-preview.txt
• unnamed
• use-bytestring-functions-dropwhile-and-break-instead-of-ours.dpatch

Self-accept, goes in 2.10 as optimization.