4.2 Introduction to LAN Switching  
  4.2.6 Ethernet switch latency  
Latency is the period of time from when the beginning of a frame enters to when the end of the frame exits the switch. Latency is directly related to the configured switching process and volume of traffic.

Latency is measured in fractions of a second. With networking devices operating at incredibly high speeds, every additional nanosecond of latency adversely affects network performance.