Some more specific questions about NRF24

I am using the TMRh20 library for nrf24 and there are some methods, I didn't understand their main purpose, advantage and usage. I will be very happy if you help me to understand these codes better. I checked the internet but I cannot find the an exact answer for my questions.

What is the purpose and usage of setPALevel in nrf24 ? and if I change the RF24_PA_MIN to RF24_PA_MAX, I get better performance on the wireless communication ?
radio.setPALevel(RF24_PA_MAX);

What is the purpose and usage of setDataRate in nrf24 ?
radio.setDataRate(RF24_250KBPS); // reducing bandwidth

If I increase the RF24_250KBPS to RF24_1MBPS or RF24_2MBPS , is it increasing the performance of the nrf24 module's wireless communication between transmitter and receiver ? thank you.

Why these codes are needed in the setup section with which way I can increase the performance of my nrf24 ?
radio.setAutoAck(1); // Ensure autoACK is enabled
radio.setRetries(2,15); // Optionally, increase the delay between retries & # of retries
radio.setCRCLength(RF24_CRC_8); // Use 8-bit CRC for performance

Apart from these, I have another very important question. When I keep the receiver code short then the execution of commands ,that are listened from transmitter, is very fast and happens in time.

However, when I write lot's of code on the receiver sketch of Arduino, then there are some 1 or 2 seconds delays to execute the commands that are sent from the transmitter to the receiver for the robot which ,for example, from transmitter I send the some commands to make robot move but because of the reasons I mentioned above, robot starts moving after some delay. So, is there any way to lower this 1-2 second delays when we use nrf24 ? thank you.

The data sheet for the nrf24 chip has the exact answers to ALL of your questions.

Paul

You can also see the comprehensive documentation for the TMRh20 nrf24 library here, which has a description of each class:

http://tmrh20.github.io/RF24/classRF24.html#adedac579590a668ae97baccab284de8a

For example setPALevel:

void RF24::setPALevel ( uint8_t level )
Set Power Amplifier (PA) level to one of four levels: RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH and RF24_PA_MAX

The power levels correspond to the following output levels respectively: NRF24L01: -18dBm, -12dBm,-6dBM, and 0dBm

SI24R1: -6dBm, 0dBm, 3dBM, and 7dBm.

Parameters
level Desired PA level.
Definition at line 1379 of file RF24.cpp.