What would you do if the service responds slowly to read requests and writes to the database slowly?

First, it is necessary to conduct diagnostics to understand the causes of slow performance:

1. Profiling and logging — measure response times at each stage: reading, processing, writing.
2. Database check — possibly slow queries due to lack of indexes, locks, or overload.
3. Query optimization — rewrite heavy queries, add indexes, use caching.
4. Parallelization and asynchrony — if possible, perform write operations asynchronously to avoid blocking the main thread.
5. Server resources — check CPU load, memory, disk, network.

Example of read optimization using caching in Java:

// Using a simple cache for frequently requested data
Map<String, Data> cache = new ConcurrentHashMap<>();

public Data getData(String key) {
    return cache.computeIfAbsent(key, k -> database.read(k));
}

If the issue is with writing, consider using a message queue for asynchronous writing, for example, with Kafka or RabbitMQ.