Ok, using BrowserUk's suggestions we improved the speed by 25.5 percent.

I am not a perl whiz, and do not know how to "remove a level of scope" in the syntax below.

"use integer" helps, and more so (i think) when I moved it outside of the loop.

the "grep $_ &1, @LongListOfIntegers" doesn't do anything since I know the values are all odd.

The last idea provided the most savings. I do need both values as keys in the hash, since I am using this as a lookup in subsequent steps. 

{
  use integer;
  foreach my $i1 ( 0 .. $#LongListOfIntegers) {
    my $v = $LongListOfIntegers[ $i1 ];
    foreach (@LongListOfIntegers[ $i1+1 .. $#LongListOfIntegers]) {
      if (($v & $_) == 1) {
        $MatchedIntegers{$v}{$_}=();
        $MatchedIntegers{$_}{$v}=();
      }
    }
  }
}

[download]
Thanks. Now I am going to investigate kikuchiyo's comments.

In reply to Re^2: Need a faster way to find matches by remzak
in thread Need a faster way to find matches by remzak

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