Limited event posting with Simconnect

Hi,

I'm experiencing some lag when sending a lot of events using Simconnect to connect to PMDG 737NGX:
EVT_MCP_ALTITUDE_SELECTOR

The PMDG_NGX_Control structure is used to send the actual event:
struct PMDG_NGX_Control {
    unsigned int Event;
    unsigned int Parameter;
};

I'm calling the SimConnect_SetClientData function to set this structure with the appropriate event and paramenter.
Once I receive SIMCONNECT_RECV_ID_CLIENT_DATA for the NGX structure, I check if Event variable has returned to 0. If it has, I will send the next event (if any).

This seems to work okay, the problem is that is quite slow. I get the feeling that it is tied to the frame rate of the sim.
We have it hooked up to a hardware rotary encoder, which can generate quite a lot of events. You will see a definite lag in the sim as it is trying to catch up.

Please let me know if my way of doing this is wrong. Hopefully there is a quicker way to send events.

Any help is appreciated,

Corjan