Our latency is unstable: 5 requests of 200ms, and the 6th — 300-350ms. Meanwhile, the metrics inside the application are equally stable. Which side would you look at?

If metrics inside the application are stable, but external latency is unstable (5 requests around 200ms, 6th — 300-350ms), consider the following points:

• Network delays and instability: there may be issues at the network level — peak loads, packet loss, routing.
• Load balancer: it might distribute requests unevenly, or one of the servers is slower.
• Caching and external dependencies: the 6th request might take a different path, such as bypassing cache or calling an external service.
• Infrastructure issues: for example, GC pauses, disk problems, or other system delays.

I recommend checking the load balancer logs, monitoring the network, verifying server configuration and status, and tracing requests to identify bottlenecks outside the application.