Check out the Mikrotik routers www.routerboard.com these are linux based and rock solid. The HAp AC Lite retails for $50
https://routerboard.com/RB952Ui-5ac2nD
Also these routers are like swiss army knives they can do everything from DHCP Server to full BGP and MPLS. The only limitation is the CPU, Ram and the Interfaces.
Actually the Linux kernel is rather fast if used right.
The Mikrotik CCR1036 series routers have a 36 core tile CPU with each core running at 1.2ghz it can cram out 15 million pps. https://www.youtube.com/watch?v=UNwxAjJ4V4A
Also these routers are like swiss army knives they can do everything from DHCP Server to full BGP and MPLS. The only limitation is the CPU, Ram and the Interfaces.