First-party and lovingly-crafted indie apps do use native technologies, and often care about performance, but it feels like everything else uses various bloated cross-platform frameworks.

The fact that nothing on my modern day iPhone feels any faster than my iPhone 4 did, when the current phones are 10x more powerful tells me that developers consistently spend >= 100% of the yearly Moore's Law dividend on framework bloat, spyware, and useless animations. If we could run iOS 6 and its matching apps on modern hardware, and set animation duration to 0 like jailbreaks used to allow, imagine how fast our phones would be!