Not sure what you mean with that? So you use the default configuration? Which would be:
clusterSize: "3"
partitionCount: "3"
replicationFactor: "3"
cpuThreadCount: "2"
ioThreadCount: "2"
I think you need to increase your partition count and thread count to get more throughput here.
You need to play around a bit with these configuration to find the optimal setting for your use case I would say.
Greets
Chris