I must be a fool because Lollipop runs quite a bit better on my Moto G than Kitkat. I'm talking about overall responsiveness, fluidity of animations, time it takes for apps to launch, random hitches, system memory footprint, how much RAM individual apps take, how often apps get flushed off memory, how often Swiftkey crashes (all the time in kitkat, never in lollipop) how often I get launcher redraws, etc. On kitkat, the lockscreen control widget for Spotify would crash all the time since it ran out of memory. Very annoying since that's the process that allows you to pause music using headphones. Ir hasn't crashed once in almost a month with Lollipop.
This is what memory usage looks like on 5.0.1
I rarely had over 100MB available on kitkat at any given moment. And when you are on 1GB of RAM, every little byte counts.
ART is faster than dalvik and it uses less memory. That's not an opinion.
It might not be as noticeable on high end phones, since you can throw powerful hardware at any software and it'll run ok, but on mid to low range devices kit kat is not a very pleasant experience. It's a memory hog.