Why is regex so slow?

[Roy Smith]

In article <mailman.3549.1371576854.3114.python-list at python.org>,
Mark Lawrence  <breamoreboy at yahoo.co.uk> wrote:

> Out of curiousity have the tried the new regex module from pypi rather 
> than the stdlib version?  A heck of a lot of work has gone into it see 
> http://bugs.python.org/issue2636

I just installed that and gave it a shot.  It's *slower* (and, much
higher variation from run to run).  I'm too exhausted fighting with
OpenOffice to get this into some sane spreadsheet format, so here's
the raw timings:

Built-in re module:
0:01.32
0:01.33
0:01.32
0:01.33
0:01.35
0:01.32
0:01.35
0:01.36
0:01.33
0:01.32

regex with flags=V0:
0:01.66
0:01.53
0:01.51
0:01.47
0:01.81
0:01.58
0:01.78
0:01.57
0:01.64
0:01.60

regex with flags=V1:
0:01.53
0:01.57
0:01.65
0:01.61
0:01.83
0:01.82
0:01.59
0:01.60
0:01.55
0:01.82