High Redis latency on first call (v4)

Hi

So, it works for some time now in several sites, but it seems that there is some kind of latency on the first call. It is fast afterwards

Searching the web, it looks like a known behavior with the wrong config:
https://stackoverflow.com/questions/45420029/redis-acquiring-connection-time-with-php-clients

How can redis be configured to mitigate this behavior?

Thanks