This app was mentioned in 1 comment, with an average of 1.00 upvote
I liked the peanut app. I did something similar as a bedtime project, but it didn't look nearly as nice. Though, looks like their version was a flunk commercially: andriod and apple. Very little use on either platform.
As for the speed, there are all sorts of methods: using css instead of background images, reducing needless javascript, deferred/async loading of resources. Not sure in particular what they're doing right, but you could grok the code a little and see.