Kafka slow join - apache-kafka

Question

I am running confluent-oss-5.0.0-2.11 kafka server with default server properties (from etc/kafka) on my local PC and created topics test1 and test2 with the below command
kafka-topics --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 –topic
Below are the environment properties I have
props.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 10);
props.put(BATCH_SIZE_CONFIG, 16384);
props.put(LINGER_MS_CONFIG, 10);
props.put(BUFFER_MEMORY_CONFIG, 33554432);
props.put(METADATA_MAX_AGE_CONFIG, "10");
Here is what the producer does
String padded = RandomStringUtils.random(2000, true, true);
for(int i=0;i<1000000;i++) {
kafkaProducer.send("a" + i, "aa" + padded + i, "test1");
kafkaProducer.send("a" + i, "bb" + padded + i, "test2");
}
kafkaProducer.flush();
Here is what the consumer does
KTable<String, String> a = builder.table("test");
KTable<String, String> b = builder.table("test1");
a.join(b, new ValueJoiner<String, String, String>() {
#Override
public String apply(String value1, String value2) {
return "a" + value1;
}
}).toStream().to("finalTopic");
And below is how I observe the performance of "finalTopic" population
AtomicInteger counter = new AtomicInteger();
builder.<String, String>stream("finalTopic").peek((key, value) -> {
if(counter.incrementAndGet()%1000 == 0) {
logger.info("date {}, final join key {}, value size {}, joins performed {}", System.currentTimeMillis(), key, value.length(), counter.get());
}
});
I managed to get around 55,000 messages per second getting above messages into different Kafka topics using producer.
However, on the consumer side, the rate of messages are being populated into "finalTopic" is at around 110 messages per second.
Any pointer is appreciated!