$tofind = "some string";

while(<DATA>) {
    push @list, $_;
} 

# Make a compiled list with qr
@clist = map qr/$_/, @list;

# Now run the two lists
foreach (@list) {
    print "Found $tofind\n", last if($tofind =~ /$_/);
}

foreach (@clist) {
    print "Found $tofind\n", last if($tofind =~ /$_/);
}