@rozpruwacz sending a single message on nrf24 takes about 1ms, which is 10x the time it takes to do an analogRead (1ms = 1,000 us). So unless you need to check the button more than several thousand times per second you're going to be fine.
Quick calculation example: let's say you have 10 buttons and you want to check each them 50 times per second (which is much faster than a human can react, normal reaction time is about 1/10 to 1/20 second). That would require checking 10 * 50 * 100us = 50,000us = 50 ms. You'll still have 950ms to do everything else. So even an extreme case would not be a problem.