Evaluation of long chains of "+" takes disproportionally long time.

[pmachata]

$ time ./dwgrep/dwgrep '()*******************'

real    0m0.006s
user    0m0.006s
sys 0m0.000s
$ time ./dwgrep/dwgrep '()+++++++++++++++++++'

real    0m6.406s
user    0m6.052s
sys 0m0.362s

It looks quadratic in number of +'s. X+ is translated as XX*, I suspect the long chain of +'s simply leads to a huge number of X instances.