.NET Framework 4.6 new JIT compiler version RRS feed

  • Question

  • Hi,

    I read that .NET 4.6

    features a new version of the 64-bit JIT compiler (originally code-named RyuJIT).

    Performance advantages of the new compiler are extended also to C# programs compiled Any CPU targetting the (old) .NET 4.0 ?

    These advantages are related to the compilation time or also execution time ?

    Thank you very much in advance


    Wednesday, July 22, 2015 2:44 PM


  • The JIT compiler impacts any code that is JITted on the target machine for CLR v4. This has nothing to do with VS compilations.  At runtime your managed code is compiled to native code for actual execution and this is where the JIT compiler comes into play. If the machine your code is running on has .NET 4.6 and your app is running as x64 then it'll take advantage of the faster compilation and any optimizations to the generated code.  The goal of the rewrite was to get to a single base set of code for JIT, not so much generating more optimal code from my understanding.  Now that it is in place though you can expect to see execution time increases going forward. Compilation time with the new compiler is faster so you will see some execution time increases for that but as far as generating more optimal code I believe that is coming in the future.

    If your code is compiling for x86, AnyCPU on an x86 OS or targeting CLR v1 or v2 then you won't be using the new 64-bit JIT compiler. 

    Michael Taylor

    • Marked as answer by Manuel Marini Wednesday, July 22, 2015 4:36 PM
    Wednesday, July 22, 2015 3:49 PM