Yes, and you should get a message in the “cconsole.log” file (limit license exceeded).
If there is no notification in the "cconsole.log" it's probably another problem.

Hi @Anil Mathew 
It seems to be the concurrent users license behaviour.

There is a 10 seconds "grace period".
Check your kind of licence.

As I use IRIS, with a "core base" license, I haven't encountered this problem.

I never tested by myself, but maybe the parameter "UseSession = 1" can help you.
Take a look in the %CSP.REST class documentation.

Since I work a lot on performance issues, I tend to agree with your comments @Stephen Canzano .  

For me, the truth is the query plan and the number of GloRef \commands executed at runtime.

@Irene Mykhailova I wonder how the result would with a clear cache between each query.

We can clear the cache with : 

d ClearBuffers^|"%SYS"|GLOBUFF()

don't do this in production ;-)

In my own experience, the efficiency of the IRIS cache can hide problems or be misleading.

In recent versions, I think the difference could be marked for embedded SQL on the first run only if “sqlcompile mode=deferred” is not used.  deferred mode is the default mode for years and can be overridden with a compile qualifier (and maybe a system-wide parameter).