After 18 months of battling 2.1-second p99 message processing latency with RabbitMQ 3.12, our team migrated to Kafka 4.0 and slashed that metric by 55% to 945ms, while reducing infrastructure costs by 32% in the first quarter post-migration. This isn't a marketing pitch—it's a data-backed breakdown of why we made the switch, how we executed the...