If you are using a modded handheld radio (e.g OTAC Gear's MPU-5 is 50km), and many people transmit at once, regardless of the frequency, server FPS will drop significantly. We tested by having 30~ players stand in a circle, we told them to all transmit at once using our modded radio. Server FPS dropped to 1 and effectively froze, took a while to catch up

We then got them to to test using vanilla handheld radios and had no problems. The only reason I mention the range as a problem is because I've read elsewhere that it's a problem with modded radios that have a large range (e.g any modern radio mod)