Server received the request at Time A, then sent out response packets at Time B. Client received the packet, sent out client ACK to server. Server received the ACK at Time C, and then sent out the last packet to client.
FxV processing time is calculated by finding the time difference between Time A and Time B, while the client time is calculated by finding the time difference between Time B and Time C. APM execution time is the amount of time spent processing on the server in a single thread due to the original request. Therefore, the server execution time captured in APM can be much different from the FxV processing time.