$ perle 'my $re; BEGIN { $re = qr{(?x: [%/?<>\\:*|":] )} } say q{%/?<>\\:*|":} =~ s/$re/_/gr'
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$ perle 'say q{%/?<>\\:*|":} =~ y{%/?<>\\:*|":}{_}r'
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$ for i in {1..5}; do perle 'use Benchmark qw{cmpthese}; my $re; BEGIN { $re = qr{(?x: [%/?<>\\:*\|":] )} }; my $str = q{%/?<>\\:*|":}; cmpthese 0 => { s => sub { $str =~ s/$re/_/gr }, y => sub { $str =~ y{%/?<>\\:*|":}{_}r } }'; done
       Rate     s     y
s  212144/s    --  -96%
y 5420361/s 2455%    --
       Rate     s     y
s  204213/s    --  -96%
y 5632150/s 2658%    --
       Rate     s     y
s  201600/s    --  -97%
y 5771041/s 2763%    --
       Rate     s     y
s  204103/s    --  -96%
y 5026909/s 2363%    --
       Rate     s     y
s  222651/s    --  -96%
y 5600560/s 2415%    --