In this case there should be no win to trying to optimize. The RE engine is smart enough to find a much better optimization behind your back. (Find the fixed string through Boyer-Moore, match the RE around that optimization.)

In general while backtracking is good to know about, most of the time it is not a problem. The exceptions are cases like this: 

foreach my $i (1..40) {
  slow_match($i);
}

sub slow_match {
  my $count = shift || 20;
  my $str = ("yada " x $count) . "yad";
  print "Trying to match $count iterations..";
  die "Huh?" if $str =~ /^(\s*yada\s*)*$/;
  print "Done\n";
}

[download]
As for the optimization you mention, for ones which do not use "special features" (eg backreferences within the match, lookaheads, etc) it is possible to execute any match in guaranteed time. Perl does not, however, do this...

In reply to Re (tilly) 1: Avoiding regex backtracking by tilly
in thread Avoiding regex backtracking by Aristotle

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