In the .NET ecosystem, there are three primary types of Just-In-Time (JIT) compilers:
Pre-JIT Compiler:
The Pre-JIT compiler compiles the entire source code into native machine code in a single compilation cycle. This process is typically performed at the time of application deployment using the Native Image Generator (NGen). The advantage of Pre-JIT is that it eliminates the initial compilation delay, leading to faster application startup times since the native code is already available[1][2][4][6].
Normal JIT Compiler:
The Normal JIT compiler compiles methods at runtime, but only when they are called for the first time. Once a method is compiled, it is stored in memory and reused for subsequent calls, which improves performance by avoiding repeated compilation. This type of JIT compilation balances the need for quick startup times with the flexibility of compiling only the necessary code[1][2][4][5][6].
Econo JIT Compiler:
The Econo JIT compiler also compiles methods at runtime as they are needed, but it removes the compiled code from memory after execution to save memory. This type of JIT compilation was designed to be more memory-efficient but is now considered obsolete and has been deprecated since .NET 2.0[1][2][4][6].
