# mine.pl

sub show {
    my @data = @_;
    for (@data) {
        s/\266/%B6/g;
        s/\267/%B7/g;
        tr/ /\267/;
        s/\t/ -> /g;
        s/\n/\266\n/g;
    }
  return wantarray ? @data : join'',@data;
}

@data = (<DATA>)[0..7];
my $start = time;
for (0..100000) { my @new = show(@data) }
printf "Mine takes %d seconds", (time - $start);

__DATA__
	tab
    4 spaces, trailing tab	
	    tab and 4 spaces
		
 -> tab¶
····4·spaces,·trailing·tab -> ¶
 -> ····tab·and·4·spaces¶
 ->  -> ¶
¶


# yours.pl

my %mapping = (
    "\t"   => ' -> ',
    " "    => chr(0267),
    "\n"   => chr(0266)."\n",
    "\266" => '%B6',
    "\267" => '%B7',
	);

my $pattern = qr/([@{[join '', keys %mapping]}])/;

sub show {
    my @data = @_;
    s/$pattern/$mapping{$1}/g for (@data);
    return wantarray ? @data : join'',@data;
}

@data = (<DATA>)[0..7];
my $start = time;
for (0..100000) { my $new = show(@data) }
printf "Yours takes %d seconds", (time - $start);

__DATA__
	tab
    4 spaces, trailing tab	
	    tab and 4 spaces
		
 -> tab¶
····4·spaces,·trailing·tab -> ¶
 -> ····tab·and·4·spaces¶
 ->  -> ¶
¶