I have a div with this css class: .pos { -webkit-filter: brightness(0.5); -moz-filter: britghtness(0.5); -o-filter: brightness(0.5); -ms-filter: brightness(0.5); filter: brightness(0.5); } And on my iPhone it runs slow. If I remove those attributes everything goes fast. How can I use these attributes without slowing the page down?