It may be slower in some circumstances.    :-)

$ perl -le'
my $x = "set manager logport [<0-10000>]
  set manager secondary ip A.B.C.D
  set mgmtport auto
  set mgmtport speed (10|100) duplex (full|half)
  set portsettletime <0-300>
  set sensor gateway A.B.C.D
  set sensor ip A.B.C.D E.F.G.H";

my $y = q/set mgmtport speed (10|100) duplex (full|half)/;

use Benchmark q/cmpthese/;

cmpthese -10, { regex => q[my $z = 1 if $x =~ /\Q$y\E\s/i], index => q
+[my $z = 1 if index( lc $x, lc $y ) >= 0] };
'
           Rate index regex
index 1475956/s    --  -24%
regex 1932798/s   31%    --
[download]

Update: The regex gets even faster if you use the /o option.

           Rate index regex
index 1431366/s    --  -33%
regex 2139276/s   49%    --
[download]