std.regex performance

[Andrej Mitrovic]

Here's some runs on win32, -release -O -inline (I just generated
134,950 duplicate words) :

2.054: 82 msecs (467KB exe)
2.055: 77 msecs (505KB exe)
2.056: 84 msecs (1095KB exe)
2.057: 3380 msecs (1179KB exe)
2.058: 3373 msecs (630KB exe)

Compile times are different too:
2.054: timeit dmd -release -O -inline test.d
Elapsed Time:     0:00:01.281

2.055: timeit dmd -release -O -inline test.d
Elapsed Time:     0:00:01.500
2.056: same

2.057: timeit dmd -release -O -inline test.d
Elapsed Time:     0:00:06.296

2.057: timeit dmd -release -O -inline test.d
Elapsed Time:     0:00:08.093