if(!ob_start('ob_gzhandler'))
 {
    echo 'NO GZ';
    ob_start();
 }
 
echo '<script type="text/javascript">
$(document).ready(fuction() {
});
</script>';
ended up with 93 bytes
 
<?php
if(!ob_start('ob_gzhandler'))
 {
    echo 'NO GZ';
    ob_start();
 }
 
echo '<script type="text/javascript">
$(fuction() {
});
</script>';
Ended up with 77 bytes
 
So you ended up with 16 Bytes worth of savings on this super simple test.