The problem is binmode doesn't change the layer of the filehandle, it adds a new layer.

Try appending the following line to your test: 

warn PerlIO::get_layers($handle{$file});

[download]
And then try to count how many times the string encoding(utf-8-strict)utf8repeats. In my case, it was 922 × 
my @l = grep /utf-?8/, PerlIO::get_layers($handle{$file});
warn @l / 2;

[download]

To fix that, clear the layers before applying new ones by starting with :raw: 

        binmode $fh, ':raw:encoding(UTF-8)';

[download]
The result becomes agreeable: 
          Rate   close noclose
close   2137/s      --    -28%
noclose 2951/s     38%      --

[download]
And the warning now shows a pretty low number.

Updated: Show how to count the repeated layers.

Update 2: On MSWin, you might need to add :crlf after :raw if needed, too.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In reply to Re: Why is using binmode on a file handle 77 times slower than just closing it and re-opening? by choroba
in thread Why is using binmode on a file handle 77 times slower than just closing it and re-opening? by Maelstrom

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.