S2C : Optimize reliability/speed transmission

I’m using pro s2c, API 2
Polled method is used to avoid collisions.
8 EndPoints (minus 30meters)
s2c / Coordinator / MacOS / Python <-> s2c / EP / Arduino

Do I need router ? (to optimize the transmission speed, avoid intermediaries)?
If we fixed with xctu, for point-end, the recipient, ie the coordinator of DH, DL, that he improves? the speed of transmission; although we never made broadcast, and by API recipients for each packet is fixed?
Can we increase the Transmit retry count for TX_status?
What are the ways to minimize number of retries (ACK) in TX status ?

Can anybody help me optimize these issues?

Best regards

There is really nothing you can do other then adding some routers to act as parents. Even then, you can only buffer the smaller of either 100 bytes or two indirect messages for the same node. Once that packet has been received, you can then add another packet. If you want fast transmissions, then you need to switch to all routers instead of end nodes.