You're right about a few things, but I don't think you're painting a true picture of things.
Yes, your router uses much CPU for NAT. That's because it is a complex process which requires mangling the packets and keeping lots of state in a big table.
QoS however is relatively cheap. It's merely looking at fixed offsets in the IP packets and deciding which of those (mangled) packets must go now and which can go later. It requires some extra memory for some extra packet-queues, and a lookup in one of iptables' smallest rulesets. That's about it.
Yes, I routed things at slower speeds, but you got to have a perspective on things: You must NAT all the traffic, but only need to QoS the outgoing traffic.
This means that if the downstream speeds have increased 100x recent years while upbound speeds only 10x (which is my fair assesment of the market), your NAT cost is now 110x higher, while the QoS cost is merely 10x.
And QoS was the cheap load. If your router is already buried in other work, I'm sure QoS will feel extra painful, but so would anything else. On a healthy load you probably wont see it in the load-graphs at all.
Also worth keeping in mind is that QoS as a feature has diminishing returns the higher upload-rates you have. If you have 128kbps upload, making sure the right packets get out first is excessively important. If you have Gigabit upload, not only will QoS be more expensive, but you are almost guaranteed to have no benefit from it what so ever.
So yeah, I stand by my argument. QoS is not a heavy feature, even though marketed as such.
Yes, your router uses much CPU for NAT. That's because it is a complex process which requires mangling the packets and keeping lots of state in a big table.
QoS however is relatively cheap. It's merely looking at fixed offsets in the IP packets and deciding which of those (mangled) packets must go now and which can go later. It requires some extra memory for some extra packet-queues, and a lookup in one of iptables' smallest rulesets. That's about it.
Yes, I routed things at slower speeds, but you got to have a perspective on things: You must NAT all the traffic, but only need to QoS the outgoing traffic.
This means that if the downstream speeds have increased 100x recent years while upbound speeds only 10x (which is my fair assesment of the market), your NAT cost is now 110x higher, while the QoS cost is merely 10x.
And QoS was the cheap load. If your router is already buried in other work, I'm sure QoS will feel extra painful, but so would anything else. On a healthy load you probably wont see it in the load-graphs at all.
Also worth keeping in mind is that QoS as a feature has diminishing returns the higher upload-rates you have. If you have 128kbps upload, making sure the right packets get out first is excessively important. If you have Gigabit upload, not only will QoS be more expensive, but you are almost guaranteed to have no benefit from it what so ever.
So yeah, I stand by my argument. QoS is not a heavy feature, even though marketed as such.