The reason for this is the networking limitations of each instance type. DF consistently reaches the networking limits for each instance type in the cloud. On

The reason for this is the networking limitations of each instance type. DF consistently reaches the networking limits for each instance type in the cloud. On r6g it's 1.4M qps and then it's saturated on interrupts due to ping pong nature of the protocol. This is why pipelining mode can reach several times higher throughput - your messages are big. c6gn is network-enhanced instance with 32 network queues! it's the most capable instance in AWS network-wise. This is why DF can reach there > 3.8M qps.