$ time perl -e '($d)  = map {$1 if /(000)/} 1..999;'

real    0m0.070s
user    0m0.031s
sys     0m0.046s

$ time perl -e '($d)  = map {$1 if /(000)/} 1..9999999;'

real    0m18.116s
user    0m17.674s
sys     0m0.436s