Snapchat is terrible on Android. I'm surprised it got so popular (when FB had a real heavy Android app I feel like a lot of people were using the web interface instead).
And that feature only looks kind of bragging to me: "hey, look at how cool we are", and I am sure some users will not even notice it.
Anyway, don't they test it and see how slow it ?
Or are they one of those company only interested in iOS and only developing for Android marginally?