Nice one++. I like the step back you took. The OP's original 2 pass idea applied to a limited range that avoids its problem and Whamo! Fewer, bigger chunks and more of the work done by the regex engine. Neat. And In most of the variations I tried it was 30% to 36% quicker than the next fastest. The only time it looses out is on a very sparse string, but that's inevitable. 

D:\Perl\test>256024 -N=-1 -LEN=10 -SPARSE=10 -CHECK
        Rate  dio1  dio2  buk1  buk2  ari2 enlil  dio3  buk3
dio1  35.6/s    --  -39%  -62%  -62%  -64%  -80%  -81%  -82%
dio2  58.2/s   63%    --  -38%  -38%  -41%  -67%  -69%  -71%
buk1  93.2/s  162%   60%    --   -0%   -5%  -48%  -50%  -54%
buk2  93.2/s  162%   60%    0%    --   -5%  -48%  -50%  -54%
ari2  97.9/s  175%   68%    5%    5%    --  -45%  -48%  -51%
enlil  178/s  400%  206%   91%   91%   82%    --   -5%  -11%
dio3   188/s  427%  222%  101%  101%   92%    5%    --   -7%
buk3   201/s  464%  245%  115%  115%  105%   13%    7%    --

Ari1:Test not performed
Ari2:A7AAB2BB....____....____....____....____....____....____.
buk1:a7aab2bb....____....____....____....____....____....____.
buk2:a7aab2bb....____....____....____....____....____....____.
buk3:a7aab2bb....____....____....____....____....____....____.
dio1:a7aab2bb....____....____....____....____....____....____.
dio2:a7aab2bb....____....____....____....____....____....____.
dio3:a7aab2bb....____....____....____....____....____....____.
enll:a7aab2bb....____....____....____....____....____....____.


D:\Perl\test>256024 -N=-1 -LEN=10
       Rate  dio2  dio1 enlil  dio3  buk3  buk2  buk1  ari2
dio2  219/s    --   -5%  -25%  -25%  -26%  -38%  -39%  -54%
dio1  230/s    5%    --  -21%  -21%  -22%  -35%  -35%  -51%
enlil 290/s   32%   26%    --   -1%   -2%  -18%  -19%  -39%
dio3  292/s   33%   27%    1%    --   -1%  -18%  -18%  -38%
buk3  296/s   35%   29%    2%    1%    --  -17%  -17%  -37%
buk2  355/s   62%   54%   22%   22%   20%    --   -0%  -25%
buk1  356/s   63%   55%   23%   22%   20%    0%    --  -25%
ari2  473/s  116%  105%   63%   62%   60%   33%   33%    --

[download]

As I believe was once said to Oscar Wilde, "I wish I'd thought of that" :)

Your right on the code block assertion too, -- I wondered what the right term for that was -- it is the biggest hit on performance of those solutions.

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller

In reply to Re: Re^4: Replace zero-width grouping? by BrowserUk
in thread Replace zero-width grouping? by tinypig

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