And to get the index with, and the two different cases:

#!/usr/local/bin/perl -w

use Benchmark;

$count = 1_000_000;
my $thing = "thing";

print "Match eq => ", check_eq(), "\n";
print "Match rx => ", check_rx(), "\n";
print "Match idx => ", check_idx(), "\n";

timethese( $count, {
   'eq' => sub{ check_eq() },
   'rx' => sub{ check_rx() },
   'idx' => sub{ check_idx() }
} );
 $thing = "asdjgfakjgfashdf___thing___asklfhklajsdhlajsdf";

print "Match eq => ", check_eq(), "\n";
print "Match rx => ", check_rx(), "\n";
print "Match idx => ", check_idx(), "\n";

timethese( $count, {
   'eq' => sub{ check_eq() },
   'rx' => sub{ check_rx() },
   'idx' => sub{ check_idx() }
} );

sub check_eq {
    ($thing eq "thing")?1:0;
}
sub check_rx {
    ($thing =~ /thing/)?1:0;
}
 $i = 0;
sub check_idx {
    ((index $thing,'thing') != -1)?1:0;
}
[download]

Result:

Match eq => 1
Match rx => 1
Match idx => 1
Benchmark: timing 1000000 iterations of eq, idx, rx...
        eq:  4 wallclock secs ( 3.40 usr +  0.66 sys =  4.06 CPU) @ 24
+6305.42/s (n=1000000)
       idx:  6 wallclock secs ( 4.01 usr +  0.86 sys =  4.87 CPU) @ 20
+5338.81/s (n=1000000)
        rx:  5 wallclock secs ( 4.30 usr +  0.90 sys =  5.20 CPU) @ 19
+2307.69/s (n=1000000)
Match eq => 0
Match rx => 1
Match idx => 1
Benchmark: timing 1000000 iterations of eq, idx, rx...
        eq:  3 wallclock secs ( 3.38 usr +  0.62 sys =  4.00 CPU) @ 25
+0000.00/s (n=1000000)
       idx:  6 wallclock secs ( 4.18 usr +  1.05 sys =  5.23 CPU) @ 19
+1204.59/s (n=1000000)
        rx:  6 wallclock secs ( 4.49 usr +  1.05 sys =  5.54 CPU) @ 18
+0505.42/s (n=1000000)
[download]

T I M T O W T D I