begin dbms_session.modify_package_state ( dbms_session.reinitialize ); end; 

I asked around internally - they are slightly different.

"dbms_session.modify_package_state ( dbms_session.reinitialize );" is re-initialises the package, ie, like a "first" instantation, and thus any package memory that was in use *remains* in use (its just the state has been cleared).

RESET_STATE is "throwing away" the session state altogether (so package memory etc is included)

*Conceptually* you could think of "dbms_session.modify_package_state ( dbms_session.reinitialize );" as doing a reset_state followed by some initialisation, so it may be worth testing to see if you get an efficiency gains out of that.

However, if this is a high CPU contributor, then I'd be taking a look at how your app is using connection pooling because that's an unusual occurrence. Tens of thousands of APEX apps around the world use this call, and we rarely see anything in terms of high CPU usage.