Performance Test: Flink 1.19 vs. Spark 4.0 vs. Kafka Streams 3.8 Windowed Aggregation Throughput

A benchmark on identical event-time tumbling windows found Flink 1.19 delivered the best throughput and latency.

Spark 4.0 lagged Flink but offers broader platform reuse, making it a tradeoff between speed and ecosystem fit.

Kafka Streams 3.8 performed the worst in this test, though newer RocksDB support could narrow the gap.

The results matter because windowed aggregation is a common streaming bottleneck, shaping engine choice by speed, cost, and operations.