What is native image cache?
Create an image of an assembly using Ngen.exe tool and place it the GAC. This native image file contains compiled processor-specific machine code. Once created the runtime will automatically uses this native image each time it runs the assembly. Therefore it loads and execute faster, because it restores code and data structures from the native image cache rather than generating them dynamically. Important: The native image that Ngen.exe generates cannot be shared across Application Domains. Therefore, you cannot use Ngen.exe in application scenarios, such as ASP.NET, that require assemblies to be shared across application domains.
