If you are not using limiters, then note this from the guide;

The ALTQ framework is handled through pf and is closely tied to network card drivers. ALTQ can handle several types of schedulers and queue layouts. The traffic shaper wizard configures ALTQ and gives firewall administrators the ability to quickly configure QoS for common scenarios, and it allows custom rules for more complex tasks. ALTQ is inefficient, however, so the maximum potential throughput of a firewall is lowered significantly when it is active.

pfSense software also supports a separate shaper concept called Limiters. Limiters enforce hard bandwidth limits for a group or on a per-IP address or network basis. Inside of those bandwidth limits, limiters can also manage traffic priorities.