Yes, it looks like using substr instead of matching with capture is the most significant improvement to be made. In fact, changing the original to do that causes it to run faster than anything except Tri_Substr2. 
sub orig_substr {
    my (@a, @b) ;
    my @temp = @master;
    foreach my $value (@temp) {
    push @a, substr($value, 2) if (substr($value,0,2) eq 'a_') ;
    push @b, substr($value, 2) if (substr($value,0,2) eq 'b_') ;
    }
    print "@a <==> @b\n" if $testing;
}

[download]
Caution: Contents may have been coded under pressure.

In reply to Re^5: Can this code be optimized further? by Roy Johnson
in thread Can this code be optimized further? by samy_kumar

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.