use Data::Dumper;

use strict;
use warnings;

my %hash = (a => 3, b=> 4, c=>1 ,d=>7); 
my @sels = qw(b c); 
delete $hash{$_} foreach (@sels);
print Dumper \%hash;

##</code><code>##

use Data::Dumper;
use Benchmark qw(timethese);
use strict;
use warnings;

timethese(1000000, {
        'loop' => \&s1,
        'non-loop' => \&s2
    });

sub s1 {
	my %hash = (a => 3, b=> 4, c=>1 ,d=>7); 
	my @sels = qw(b c); 
	delete $hash{$_} foreach (@sels);
}

sub s2 {
	my %hash = (a => 3, b=> 4, c=>1 ,d=>7); 
	my @sels = qw(b c); 
	delete @hash{@sels};
}

##</code><code>##

Benchmark: timing 1000000 iterations of loop, non-loop...
      loop: 10 wallclock secs ( 9.84 usr +  0.03 sys =  9.87 CPU) @ 101276.08/s
(n=1000000)
  non-loop:  8 wallclock secs ( 6.88 usr +  0.02 sys =  6.89 CPU) @ 145116.82/s
(n=1000000)