we have the routerboard CCR1036-8G-2S, firmware 6.44.5.
We are use as gateway to internet for 1000 users.
“QUEUES, NAT and Firewall”
Average flow data 750 Mbps
If data flow exceeds 820 Mbps, the routerboard will increase the load from an average of 25 percent to 100 percent. It will help to turn off the QUEUS upload part.
If I change the Queus tree parent from “global” to the outgoing interface (for me ether2), mikrotik just limit my upload. Download in queus tree doesn’t work.
I dont know how you have your tree setup in my case i make like 10 global trees and add one rule to one global and same as in your case only for download, Ive manage to lower cpu usage form 90 in peek to 35-45 in peek.