Good old ActivePerl 5.10.1 does it in about 1.8 seconds on my Windows laptop, while Strawberry Perl 5.26 is taking quite a while (multiple minutes already). I wonder why there's such a difference.

Program for reference.

  use strict;
  use warnings;

  my $max_i = 1_000_000;

  for my $i (0 .. $max_i) {
    print "my \$x$i = $i;\n";
  }

Edit: It took 80 minutes! Wow. There must be something significantly different going on, but I wouldn't know where to look.