“Total Network I/O Checks” reports the number of times an engine polls for incoming and outgoing packets. This category is helpful when you use it with “CPU Yields by Engine.”
When an engine is idle, it loops while checking for network packets. If “Network Checks” is low and “CPU Yields by Engine” is high, the engine could be yielding too often and not checking the network frequently enough. If the system can afford the overhead, it might be acceptable to yield less often.