That has nothing to do with Kafka, or Java as a language.
Distributed big data processing systems need big data to actually be useful. Small data that fits on a single machine can also be processed on a single machine, which will always be faster than using a cluster with orchestration, distribution and network overhead.
Distributed big data processing systems need big data to actually be useful. Small data that fits on a single machine can also be processed on a single machine, which will always be faster than using a cluster with orchestration, distribution and network overhead.