>> 1. Does the QoS function load the CPU, Memory?
For every decision on a GW we will need computing resources, so - yes, also QoS has its price, and you have to decide if it is right 😉.
>> 2. Customer references using the QoS feature.
What do you expect here ? I can only tell you that QoS is widely used for VoIP and video conferencing prioritizing - this is done by making other traffic slower...
For more reading see sk30590: What is Check Point QoS?, sk32176: Limitations of Check Point QoS and the R80.30 QoS Administration Guide !
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