Don't forget to consider the performance difference when: 
$_ = "abc" x 200_000;
$string = "ab";

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UPDATE
I started with 2 million, then changed to 200,000 because I thought that would be slow enough. But I messed up. Now fixed.

In reply to Re (tilly) 1: 1 while s/// vs s///g by tilly
in thread 1 while s/// vs s///g by merlyn

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