TheĀ generate_page_header_parallax_speed filter allows you to adjust the speed at which the page header parallax script moves your background image.

The default speed is 2, and I wouldn’t suggest going much lower than 1.5. The level of effect is dependent on the height of your image, as well.


add_filter( 'generate_page_header_parallax_speed', 'tu_adjust_page_header_parallax' );
function tu_adjust_page_header_parallax() {
    return 2;