I have experienced a little bit of a slow in when a .net application runs
first. But later it never happens until the system restarts.

I understood the reason is that when ever application runs first JIT
compiler recompiles the assembly and generate a native code that is fully
compatible to our current CPU specifications if the assembly doesn’t have a
native image in its cache. Later it uses from cache hence it executes fast.

My doubts comes here, when application runs first it generate native code
and added to cache then why I am not able to see using the below command

ngen display “Assmblyname” it gives me below error.

Error: The specified assembly is not installed.

Please give me a solution for this, also if I am wrong please correct me.