Java service: response time has increased, some requests take several seconds. What will you look at first? At least 4 points.

1. Profiling and monitoring JVM: check CPU usage, garbage collector (GC), memory leaks, number of threads.
2. Logs and traces: examine logs for errors, long queries, exceptions, timeouts.
3. Database and external services: check response times for database requests, queues, locks, caching status.
4. Code and query analysis: identify slow sections, possibly new heavy queries or operations.

Additionally, you can check network load, connection pool configuration, and infrastructure status.