use strict;
use warnings;
use 5.012;
use FastBioRanges;
# use PerlIO::gzip; # I just noticed I forgot this 'use' but it worked
+ fine... how?

use Storable qw (retrieve_fd);
use Time::HiRes qw(gettimeofday tv_interval);

my $time = [gettimeofday];
open( my $fastbioranges_fh, "<:gzip",
    'fastbioranges.store.gz') or die;
my $fastbioranges = retrieve_fd($fastbioranges_fh) or die;
close($fastbioranges_fh);
say "loaded in ", tv_interval($time), " seconds";

my $n = 1000;
$time = [gettimeofday];
#say "start\tend\tcover";
for ( 1 .. $n ) {
    my $start = int rand(877878);
    my $size  = int rand(7000);
    my $end   = ( $start + $size ) % 877879 + 1;
    my $cover = $fastbioranges->num_ranges_containing( $start, $end );
    # say "$start\t$end\t$cover";
}
say "$n queries in ", tv_interval($time), " seconds";
[download]

loaded in 0.385292 seconds
1000 queries in 0.005204 seconds
[download]

# use PerlIO::gzip; # I just noticed I forgot this 'use' but it worked fine... how?

Because using ':gzip' causes perl to look for and load the appropriate module.