要解决Apache Kafka消费者始终滞后的问题，可以尝试以下几种方法：

1. 增加消费者数量：如果消费者数量较少，可能会导致消费者无法及时处理大量的消息。可以尝试增加消费者的数量，使其能够更快地处理消息。

properties.put("group.id", "my-group");
properties.put("bootstrap.servers", "localhost:9092");
properties.put("auto.offset.reset", "latest");

KafkaConsumer consumer = new KafkaConsumer<>(properties);
consumer.subscribe(Arrays.asList("my-topic"));

// 启动多个消费者
int numConsumers = 3;
List consumers = new ArrayList<>();
for (int i = 0; i < numConsumers; i++) {
    ConsumerThread consumerThread = new ConsumerThread(consumer);
    consumerThread.start();
    consumers.add(consumerThread);
}

// 消费者线程
class ConsumerThread extends Thread {
    private final KafkaConsumer consumer;

    public ConsumerThread(KafkaConsumer consumer) {
        this.consumer = consumer;
    }

    public void run() {
        while (true) {
            ConsumerRecords records = consumer.poll(Duration.ofMillis(100));
            for (ConsumerRecord record : records) {
                // 处理消息
                System.out.println(record.value());
            }
        }
    }
}

2. 提高消费者的处理能力：优化消费者的处理逻辑，以提高其处理能力。可以考虑使用多线程或异步处理来并行处理消息。

properties.put("group.id", "my-group");
properties.put("bootstrap.servers", "localhost:9092");
properties.put("auto.offset.reset", "latest");

KafkaConsumer consumer = new KafkaConsumer<>(properties);
consumer.subscribe(Arrays.asList("my-topic"));

int numThreads = 3;
ExecutorService executor = Executors.newFixedThreadPool(numThreads);

while (true) {
    ConsumerRecords records = consumer.poll(Duration.ofMillis(100));
    for (final ConsumerRecord record : records) {
        executor.submit(new ConsumerThread(record));
    }
}

// 消费者线程
class ConsumerThread implements Runnable {
    private final ConsumerRecord record;

    public ConsumerThread(ConsumerRecord record) {
        this.record = record;
    }

    public void run() {
        // 处理消息
        System.out.println(record.value());
    }
}

3. 调整消费者配置：可以尝试调整消费者的配置参数，如fetch.min.bytes、fetch.max.wait.ms和max.poll.records等。根据实际情况进行调整，以提高消费者的性能和响应能力。

properties.put("group.id", "my-group");
properties.put("bootstrap.servers", "localhost:9092");
properties.put("auto.offset.reset", "latest");
properties.put("fetch.min.bytes", 1024); // 设置最小拉取字节数
properties.put("fetch.max.wait.ms", 500); // 设置最大拉取等待时间
properties.put("max.poll.records", 100); // 设置每次拉取的最大记录数

KafkaConsumer consumer = new KafkaConsumer<>(properties);
consumer.subscribe(Arrays.asList("my-topic"));

while (true) {
    ConsumerRecords records = consumer.poll(Duration.ofMillis(100));
    for (ConsumerRecord record : records) {
        // 处理消息
        System.out.println(record.value());
    }
}

通过以上方法，可以尝试解决Apache Kafka消费者始终滞后的问题，并提高消费者的处理能力和性能。具体的解决方案可以根据实际情况进行调整和优化。