use strict;
use warnings;
use Time::HiRes 'time';
use Imager;

my $t = time;
my $i = Imager-> new( file => 'file.jpg' );
printf "image dimensions: %d x %d\n", 
    $i-> getwidth, $i-> getheight;
printf "reading: %.2f s\n", time - $t;

$t = time; $i-> copy
             -> scale( xpixels => 750, qtype => 'normal' )
             -> write( file => 'file+.jpg' );
printf "high quality resize & save: %.2f s\n", time - $t;
$t = time; $i-> copy
             -> scale( xpixels => 750, qtype => 'mixing' )
             -> write( file => 'file+.jpg' );
printf "medium quality resize & save: %.2f s\n", time - $t;
$t = time; $i-> copy
             -> scale( xpixels => 750 * 4, qtype => 'mixing' )
             -> scale( xpixels => 750, qtype => 'normal' )
             -> write( file => 'file+.jpg' );
printf "medium+ quality resize & save: %.2f s\n", time - $t;
$t = time; $i-> copy
             -> scale( xpixels => 750, qtype => 'preview' )
             -> write( file => 'file+.jpg' );
printf "low quality resize & save:\t\t %.2f s\n", time - $t;
$t = time; $i-> copy
             -> rotate( right => -90 )
             -> write( file => 'file+.jpg' );
printf "fast rotate & save: %.2f s\n", time - $t;
$t = time; $i-> copy
             -> rotate( degrees => -90 )
             -> write( file => 'file+.jpg' );
printf "slow rotate & save: %.2f s\n", time - $t;

__END__

image dimensions: 6083 x 4636
reading: 1.23 s
high quality resize & save: 6.52 s
medium quality resize & save: 1.17 s
medium+ quality resize & save: 3.84 s
low quality resize & save: 0.58 s
fast rotate & save: 3.41 s
slow rotate & save: 19.33 s