I have a page with popup that lets user select the items to be displayed.

Problem is, when the number of items (checkboxes) in this popup is too large (say 50 checkboxes), the page is running very slow on mobile when user trying to scroll through the list to check/uncheck the items.

This fiddle gives the basic idea of how the filtering looks like. 

http://jsfiddle.net/UeGPn/

In actual application I used iScroll to wrap around the checkboxes so that the popup fits the height of the screen on mobile with the capability of scrolling, instead of a very long popup that goes beyond screen height, but this shouldn't cause the performance problem as I have tried removing the iScroll and it doesn't help with speed.

I think this is related to the CSS, but I couldn't nail it down.

Any idea how to improve this?