This got me to thinking so I took your original code and made a few modifications just to see what it would do. 
#!/usr/bin/perl

use strict;
use warnings;

use Benchmark("cmpthese");

my $i = 1;

cmpthese(-1, {
   "double", q !eval q {$a = "this is a string $i"}!,
   'single', q !eval q {$b = 'this is a string $i'}!,
});

[download]
seeker:perl$> ./quotes.pl
          Rate double single
double 11712/s     --   -34%
single 17742/s    51%     --
seeker:perl$> ./quotes.pl
          Rate double single
double 11487/s     --   -30%
single 16377/s    43%     --
seeker:perl$> ./quotes.pl
          Rate double single
double 11270/s     --   -32%
single 16592/s    47%     --
seeker:perl$> ./quotes.pl
          Rate double single
double 11395/s     --   -33%
single 16905/s    48%     --
seeker:perl$> ./quotes.pl
          Rate double single
double 11894/s     --   -33%
single 17742/s    49%     --
seeker:perl$> ./quotes.pl
          Rate double single
double 11487/s     --   -32%
single 16853/s    47%     --

In reply to Re^2: To Single Quote or to Double Quote: a benchmark by bass_warrior
in thread To Single Quote or to Double Quote by NateTut

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