MikroTik Tik RB4011iGS+RM (still not sure this will handle the speed though)
Quad-core ARM 1.4GHz should have no problem. The manufacturer's throughput tests are here
For comparison, I have the much less powerful Mikrotik hEX PoE
, which has a single-core MIPS 800MHz.
In my testing, with fastpath enabled (IPv4) it routes 900M between two VLANs; with speedtest.net on 300M FTTP (including PPPoE and NAT) the CPU goes to about 33% utilisation. Without fastpath (which includes IPv6), it flatlines about 300Mbps at 100% CPU.
The measurements given by Mikrotik are ~75kpps for the hEX PoE and ~600kpps for the RB4011 (both for routing with 25 filter rules), so you can expect the RB4011 to be 8 times faster than what I see: this agrees with its four cores and roughly double clock speed.