If you install luci-app-sqm and reduce your speed about 5% I would be willing to bet you get a A+ score
Log out and log back in and you should see SQM QoS under Network
If your not sure what interface to use ssh into it and run this ifstatus wan | grep -e l3_device
I would also be interested in finding out what Htop says about your processor usage when doing a speed test, On mine even with packet steering enabled it seems to favor #3 of the processor at about 50% and the rest around 5 to 13% . At idle the most processors usage is 1% or nothing per core
EDIT: I did not have packet steering enabled for all cores, Now with it enabled all cores are less than 20 and the last core is at about 30% when doing a bufferbloat test
I tried this on one of my MT3000 units but couldn't obtain an IP address from my DHCP server on the WAN side, so I reverted to the original GL.iNet firmware.
I get the same result @ waveform.com. I was using all kinds of advanced settings but in the end the results were less good as I have now. Packet steering is enabled, SQM is enabled.
With Cake / Piece of Cake I hit the limits of the hardware sooner, around 700000 / 850000, and with a bit more latency ~2ms. Still good ofcourse, but fq_codel is providing me a better experience.
I`m not using WiFI though, I disabled it as I have a Unifi setup for that purpouse, but prefer to have everything wired as much as possible.