If you insert a big image into the DOM, MobileSafari locks up for quite a few frames (whether or not it's preloaded.) Sencha's implementation just swaps picture

If you insert a big image into the DOM, MobileSafari locks up for quite a few frames (whether or not it's preloaded.) Sencha's implementation just swaps pictures when you're not doing anything else! But most native apps can update photos while you're actually scrolling around.