Hi @balakrishnavalavala
I'm not sure this is the same problem, but we had a similar issue with deliveryParts beeing processed 8 by 8 (default wave length when not specified) in each MTAChild, and we looked in the server configuration. But this is not where we had to look.
In the delivery itself > Delivery additional parameters, then Delivery tab, and "Message batch quantity". This value is 0 to default, meaning 8 minimum. You can change this (and it can be over 256) if you need to process much more messages each call. Try this, and if it changes something for you, let us know 😉
And sorry If I didn't understand your problem.
Cedric