There isn't one answer for this. Capping GOMAXPROCS may cause severe latency problems if your process gets a burst of traffic and has naive queueing. It's best

There isn't one answer for this. Capping GOMAXPROCS may cause severe latency problems if your process gets a burst of traffic and has naive queueing. It's best really to set GOMAXPROCS to whatever the hardware offers regardless of your ideas about how much time the process will use on average.