Introduction to the nature of F# code compilation

Before we measure .NET, we need to understand the nature of F# code and the nature of compiling the F# code. Of course, we can just analyze and look at the source code. We can also try to search for any patterns of non-performing code of known bottlenecks, which will be explained in Chapter 3,Optimizing Data Structures and Chapter 7, Language Features and Constructs Optimization.

General overview of F# compiler processes and results

All of the code in F# is compiled into byte codes of the IL assembly (as it's also an assembly language) either by the F# compiler or by using F# in interactive mode (by using FSI). This IL is then run in either Debug mode as Just In Time (JIT) code is further optimized by compiling it in Release mode. Running it in Release mode will yield compiled code to be optimized for .NET native by the Ahead Of Time (AOT) method.

For more information about .NET native, here is the official explanation in the MSDN Library...