Benchmark: timing 1000000 iterations of interpolator, joiner...
interpolator:  5 wallclock secs ( 5.13 usr +  0.00 sys =  5.13 CPU) @ 194931.77/s (n=1000000)
    joiner:  4 wallclock secs ( 4.53 usr +  0.00 sys =  4.53 CPU) @ 220750.55/s (n=1000000)
                 Rate interpolator       joiner
interpolator 194932/s           --         -12%
joiner       220751/s          13%           --

##</code><code>##

#!/usr/bin/perl

my ($the,$fastest,$donut,$youve,$ever,$seen) = qw [ the fastest donut you've ever seen ];

sub joiner
{
        my $x = join ('/', $the,$fastest,$donut,$youve,$ever,$seen);
}

sub interpolator
{
        my $x = "$the/$fastest/$donut/$youve/$ever/$seen";
}

use Benchmark qw [ cmpthese ];

cmpthese ( 1000000, {

        joiner       => \&joiner,
        interpolator => \&interpolator,
}
);