The primary advantage of the sliding window protocol over the stop-and-wait protocol is efficiency. The sliding window protocol does not waste network bandwidth, while the stop-and-wait protocol does waste network bandwidth.
When using the stop-and-wait protocol, the sender must wait after every frame to receive acknowledgement from the receiver before sending the next frame. This protocol only allows for one frame being on the channel at a time. However, a sliding window protocol utilizes pipelined communication so that the full capacity of the bandwidth is used. Thus, the sliding window protocol offers better performance and higher throughput than the stop-and-wait protocol.