While setting up this site I noticed some files not found errors in dev console.
One was devicepx.js which was in the jetpack modules path.
It’s used to optionally load retina/HiDPI versions of files. I believe it would be for gravatars and since this site doesn’t use gravatars I deemed it unnecessary.
//remove unecessary queing of js file by jetpack add_action('wp_enqueue_scripts', create_function(null, "wp_dequeue_script('devicepx');"), 20);
The above code will remove the file from the enqueue list.