#! perl 
use strict;
my %cache = ( ctime => <<'RXA', cdtate => <<'RXB', fulldate -> <<'RXC' );

##... monster regex initialisation ellided;

my $refull  = qr[$cache{ fulldate }]x;
my $rectime = qr[$cache{ ctime }]x;
my $recdate = qr[$cache{ cdate }]x;

for (1..100e6) {
    "2010-02-01 01:02:03" =~ $refull;
    "2010-02-01 01:02:03" =~ $rectime;
    "2010-02-01 01:02:03" =~ $recdate;
}