Performance optimizations

[chkr1011]

When the application receives a lot of messages (try connecting with public mosquitto MQTT broker and subscribe to #), the application may become unresponsive. That's why an initial delay and an additional Dispatcher roundtrip was added after each received message.

But there is still an issue: The connection gets lost after around 1000 messages are received. Further investigation is required if this behavior is driven by the broker, the behavior of the client or a bug.

[chkr1011]

@danielmeza We may be able to reduce the delay etc.

[danielmeza]

On it! Thanks for the brocker recomendation!