Traffic Shaping

Hi

I`m a new monowall`s user and i have a wrap with the monowall os in a cf.
Mi configuration is in bridge mode (wan y opt) and the traffic shaper is working fine.
But, when we add more users to the lan, the wan connection is very slow.
We have 80 users more  or less...
I´d like to know if the os has any limit of users or it could be a hardware limitation..

  Thanks in advance..