Better to use a term "Logins per Second", instead of the term TPS. TPS of 50 looks very low for a person who comes from API invocation experience, but in fact it is a very high value. In reality what someone wants from a IAM system is how much users can login within give period of time simultaneously. They talk this as "concurrent logins"

TPS of 50 comes to 3000 logins per minute.