Slow calls from php
I’m trying to understand the problem with slow calls from PHP. The PHP application makes a call, using the REST API, to a Golang microservice 400 RPS, 7 instances of Go service, nginx as load balancer. According to the Go microservice metrics, 99% of calls are completed within 5 ms. Maximum duration of calls was 6 ms. Jaeger traces in the microservice show same. Go service just returns data from in-memory cache. However, in PHP app logs I see slow calls, lots of calls for 1 seconds, for 3 seconds.
What can be reason for it, how to fix the slowness?