Generally, the only novelties that we perceive in the operating system are those that have to do with the visual aspects, and going a little further, those that can be perceived by the performance and fluidity of the smartphone. However, there are even more relevant news than those, such as the one that could arrive soon, called Optimizer.
A new companion for ART
ART came with KitKat, being the new runtime that was going to run Java applications. He was going to happen to replace Dalvik, something he got on Lollipop. However, in reality everything goes much further than simply changing the virtual machine. There is also an element that is the compiler, which is responsible for "processing" the code to execute it. With Dalvik, the compiler was of the JIT (just-in-time) type, and it was in charge of compiling just at the moment when the code was going to be used. With Lollipop the compilation became AOT (ahead-of-time), and compiles the code before having to use it. There is no need to explain why this streamlines the operation of applications. However, the problem is that to facilitate the transition from Dalvik to ART, an AOT version of the Dalvik JIT compiler, called Quick, was used. A modification on the previous one, so to speak. Now that's what's going to change.
Say hello to Optimizer
The new compiler would have been built from scratch, and both ARM and Google have been working on it. It will be called Optimizer, and it will have current compilation technologies, as well as being compatible with compilation for 32 and 64 bits. ARM is responsible for the 64-bit section, while Google is responsible for the 32-bit. In any case, it seems that another of the novelties will be to be able to update said compiler with more novelties, so a priori we can hope that it will improve over time. Be that as it may, the most remarkable thing is the fact that Optimizer will be a compiler created precisely with the purpose of being the compiler of Java applications for Android with ART as a virtual machine, so we can expect improvements in the fluidity and operation of the smartphones, something that is always welcome.