Sorry I did not make it clear when I say "the CPU of the CPU inside the Asus GT-AX11000 Pro (BCM4912) can not handle 10Gbps OOkla Speedtest", I meant to say the test using the Asus router's built-in SpeedTest (powered by OOkla) is not showing the real capability of the Asus router. If you use a Desktop PC with 10G Ethernet Card and then connect to the 10G LAN port of the GT-AX11000 Pro, you should get much higher than what you get now.
I think GT-AX11000 Pro is a capable router to handle 10Gbps broadband. It is just you may need a 10G capable device to utilize its full potential (eg: 10G capable PC, NAS and maybe 10G capable network switch).
BTW, II also mentioned that "Maybe the Flash memory inside the router plays a part as well (I have not checked)".
Just for reference, it is the same for my Asus RT-AX86U which can not get >900Mbps download speed when running Router's built-in SpeedTest. That does not mean it can not handle 1Gbps Fibre Broadband. In fact I think it can even handle 2.5Gbps Fibre Broadband.
Rather I need to use a mini PC attached to the Asus RT-AX86U router to test the speed.
Code:
root@pve:~# ./speedtest
Speedtest by Ookla
Server: Singtel - Singapore (id = 13623)
ISP: Singtel Fibre
Latency: 1.65 ms (0.03 ms jitter)
Download: 946.60 Mbps (data used: 425.7 MB )
Upload: 946.79 Mbps (data used: 1.1 GB )
Packet Loss: 0.0%
Result URL: https://www.speedtest.net/result/c/df3032af-7457-400f-a8fa-60470e2dbf52