My pet peeve with Android is drawing apps. I bought a ZTE Open with FirefoxOS, and the first thing that struck me is that the very first drawing app I tried on a low end phone like that totally trounced every (I've tested at least two dozen) drawing app I've tested on my far faster Android phone.

On every single one of them, the brush ends up lagging ridiculously far behind my finger even with quite slow strokes, while on the FirefoxOS phone, I hardly noticed the lag unless I did fast sweeps or used a stylus (there is lag there but usually small enough that if using a finger, my fingertip obscures it)

On Windows Phone 8 everything is native, even .NET code.