Regarding C#, Microsoft hasn't invested too much on their JIT/AOT compilers optimization algorithms.
NGEN was just good enough for allowing quick application startup.
Also they didn't invest too much in optimizations in the old JIT.
Specially since .NET always had good interop to native code via C++/CLI, P/Invoke and RCW.
There were some improvements like multicore JIT in .NET 4.0 and PGO support in .NET 4.5, but not much in terms of optimization algorithms.
Hence why .NET 4.6 got a new revamped JIT called RyuJIT with SIMD support and lots of nice optimizations.
But this is only for the desktop.
.NET for the Windows Store is AOT compiled with the same backend that Visual C++ uses. In the Windows 8 and 8.1 they came up with MDIL from Singularity/Midori but with 10 they improved the workflow to what is nowadays known as .NET Native.
With the ongoing refactorings they plan to make C2 (Visual C++ backend) a kind of LLVM for their languages, similar to the Phoenix MSR project they did a few years ago.
If you watch the Build 2015 and 2016 talks, most of them are making use of C# with the new WinRT (COM based) APIs, leaving C++ just for the DX related ones.
So they are quite serious about taking their learnings from project Midori and improve the overall .NET performance.
NGEN was just good enough for allowing quick application startup.
Also they didn't invest too much in optimizations in the old JIT.
Specially since .NET always had good interop to native code via C++/CLI, P/Invoke and RCW.
There were some improvements like multicore JIT in .NET 4.0 and PGO support in .NET 4.5, but not much in terms of optimization algorithms.
Hence why .NET 4.6 got a new revamped JIT called RyuJIT with SIMD support and lots of nice optimizations.
But this is only for the desktop.
.NET for the Windows Store is AOT compiled with the same backend that Visual C++ uses. In the Windows 8 and 8.1 they came up with MDIL from Singularity/Midori but with 10 they improved the workflow to what is nowadays known as .NET Native.
With the ongoing refactorings they plan to make C2 (Visual C++ backend) a kind of LLVM for their languages, similar to the Phoenix MSR project they did a few years ago.
If you watch the Build 2015 and 2016 talks, most of them are making use of C# with the new WinRT (COM based) APIs, leaving C++ just for the DX related ones.
So they are quite serious about taking their learnings from project Midori and improve the overall .NET performance.