Thanks for posting the question to cloudera commuinity.
It would be a little too vargue to say how to check the performance. There are two things I'd suggest to do:
1) Benchmark the performance with the built-in load testing tools such as ConsumerPerformance and EndToEndLatecy.
2) Monitor the Kafka performance with the avaiable metrics:
Additionally, you may want to check the cloudera documentations on how to tune kafka broker, consumer and producers for better performance:
Hope above information helps.