[dmandel@midgard dmandel]# time perl -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m3.420s
user    0m2.590s
sys     0m0.000s

[dmandel@midgard dmandel]# time perl5.6.1 -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m0.151s
user    0m0.050s
sys     0m0.000s

[dmandel@midgard dmandel]# time perl -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m2.584s
user    0m2.580s
sys     0m0.010s

[dmandel@midgard dmandel]# time perl5.6.1 -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m0.108s
user    0m0.050s
sys     0m0.000s

[dmandel@midgard dmandel]# time perl -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m2.718s
user    0m2.570s
sys     0m0.010s

[dmandel@midgard dmandel]# time perl5.6.1 -e '$x=join("",(a..z))x100;  for
(1..100){$x =~ s/(.*?)I/$1/isge;}'

real    0m0.047s
user    0m0.050s
sys     0m0.000s