This code doesn't make any difference on the relative times on the windows 11/cygwin system. If I count the lines in the original code they are the same for both. The efficiency of populating a scalar from a file is important in general, but not really relevant to the problem here.

my $s = do {
  local $/;
  <$fh>;
};

[download]

A couple of additional pieces of info. I did 100k random seeks on the disk file and the memory file and the times were about the same. When the code is running with regex loop, it seems CPU limited.

In reply to Re^2: RE on lines read from in-memory scalar is very slow by Danny
in thread RE on lines read from in-memory scalar is very slow by Danny

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.