The initial load time on a Discourse site (with an empty cache) is typically 2–5 seconds, and with SSO, a 6–7 second load is not unusual because the SSO round-trip adds at least one extra HTTP request.
When SSO is used, the first load requires a redirect to the SSO provider and back. If the SSO provider is slow, the entire login process can be slower for first-time or logged-out users.
Load times can also be dependent on connection speed and device performance on the user side.
Ensuring that your Discourse server is adequately provisioned in terms of CPU, memory, and network speed can sometimes help improve performance, as low resource availability can lead to poor load times.