congestion using simple queue and pcq

Hello group, I need your opinions or advice:
I have a network of 300 users.
A RB1100AHx2 + nat + dhcp + 3 subnets and control the bandwidth with simple queues + pcq (as explained here https://wiki.mikrotik.com/wiki/Manual:Queues_-_PCQ_Examples), without using mangle.
It works perfect, except that every two or three days everything starts to get slow, as if the network is congested and I can’t see what it can be. It is only fixed by restarting the router.

dejo en espñaol. ya que no hablo ingles y use un traductor.
hola grupo, necesito sus opiniciones o consejos:
Tengo una red de 300 usuarios.
Un RB1100AHx2 + nat + dhcp + 3 subredes y control el ancho de banda con colas simples + pcq (como esta esplicado aqui https://wiki.mikrotik.com/wiki/Manual:Queues_-_PCQ_Examples), sin utilizar mangle.
Funciona Perfecto, salvo que cada dos o tres dias se empieza a poner todo lento, como si se congestionara la red y no puedo lograr ver que puede ser. Solo se arregla reiniciando el router.

Your information are not enough unfortunatelly…
Did you check the system resources? CPU usage? Logs? Did you Identify what exactly is slow ?