Stefan Mileschin

Programming languages seem to be cyclical. Low level languages give developers the chance to have very fast code with the minimum of commands necessary, but the closer you code to hardware the more difficult it becomes, and the developer should have a good grasp of the hardware in order to get the best performance. In theory, everything could be written in assembly language but that has some limitations. Programming languages, over time, have been abstracted from the hardware they run on which gives advantages to developers in that they do not have to micro-manage their code, and the code itself can be compiled against different architectures.

In the end, the processor just executes machine code, and job of moving from a developer’s mind to machine code can be done in a several ways. Two of the most common are Ahead-of-Time (AOT) and Just-in-Time (JIT) compilation. Each have their own advantages, but AOT can yield better performance because the CPU is not translating code on the fly. For desktops, this has not necessarily been a big issue since they generally have sufficient processing power anyway, but in the mobile space processors are much more limited in resources, especially power.

We’ve seen Android moving to AOT with ART just last year, and the actual compilation of the code is done on the device after the app is downloaded from the store. With Windows, apps can be written in more than just one language, and apps in the Windows Store can be written in C++, which is compiled AOT, as well as C# which runs as JIT code using Microsoft’s .NET framework, or even HTML5, CSS, and Javascript.

http://www.anandtech.com/show/9661/w...cus-net-native