I have constructed the following test case to compare the performance of simple regular expression and simple eq test:

use Benchmark;
@switch_me = qw / bob frnak 1 roger james /;

timethese (1000000, {
    'test_regex' => ' &test_regex; ',
    'test_eq' => ' &test_eq; '
});

sub test_regex()
{
    for(@switch_me) {
        /bob/   && do { break };
        /frnak/ && do { break };
        $_ == 1 && do { break };
    }
}

sub test_eq()
{
    for(@switch_me) {
        $_ eq "bob" && do { break };
        $_ eq "frnak" && do { break };
        $_ == 1 && do { break };
    }
}
[download]

The two subroutines are identical except for the string testing bit. The following are the test results:

Benchmark: timing 1000000 iterations of test_eq, test_regex...
   test_eq:  8 wallclock secs ( 8.45 usr +  0.01 sys =  8.46 CPU)
             @ 118161.41/s (n=1000000)
test_regex: 10 wallclock secs ( 9.22 usr +  0.01 sys =  9.23 CPU)
            @ 108307.16/s (n=1000000)
[download]

It's about (118161.41-108307.16)/108307.16 = 10% speed increase in using eq than using regular expression. It's not a great increase, but it's nevertheless faster to use eq than regular expression.