There is a Mandelbrot folder inside the Imager source tree. It looks like one can specify a filter to Imager. To build, I set the CPATH environment due to unable to find imconfig.h.

$ cpanm Imager
$ wget https://cpan.metacpan.org/authors/id/T/TO/TONYC/Imager-1.012.ta
+r.gz
$ tar xf Imager-1.012.tar.gz && cd Imager-1.012/Mandelbrot
$ perl Makefile.PL
$ CPATH=~/perl5/perlbrew/perls/perl-5.32.1/lib/site_perl/5.32.1/x86_64
+-linux-thread-multi/Imager/include make
$ make install
[download]

Running make test inside the Mandelbrot folder fails for me, so I created a script. Rendering and output to PNG takes 0.131 seconds.

use strict;
use warnings;
use Imager;
use Imager::Filter::Mandelbrot;

my $im = Imager->new(xsize => 1000, ysize => 1000);
$im->filter(type => 'mandelbrot',) or die("# ", $im->errstr, $/);
$im->write(file => 'mandel1.png');
[download]

The C code calls i_ppix per each pixel.