$ time perl -e 'for($i=0;$i<=1e7;$i++){}'                      

real    0m0.648s
user    0m0.640s
sys     0m0.005s
$ time perl -e 'for(0..1e7){}'                                 

real    0m0.354s
user    0m0.348s
sys     0m0.002s