QoS 0 and QoS 1 typically have similar throughput when using EMQX with the same hardware configuration for peer-to-peer communication, but QoS 1 may have higher CPU usage. Additionally, under high load, QoS 1 has longer message latency compared to QoS 0. On the other hand, QoS 2 usually only has about half the throughput of QoS 0 and 1.