>perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; delete $INC{'Carp/Heavy.pm'}; require Carp; require Carp::Heavy; } $t2=time; print(($t2-$t1)/$ARGV[0])" 100000
0.00475

>perl -le "$t1=time; for (1..$ARGV[0]) { delete $INC{'Carp.pm'}; delete $INC{'Carp/Heavy.pm'}; require Carp; require Carp::Heavy; } $t2=time; print(($t2-$t1)/$ARGV[0])" 100000
0.00474