I thought I'd post this since other people might find it useful—especially for quick testing purposes, as you can get a little hardware router up and running pretty quickly, and so far in my testing the Pi 4 model B can put through at least 750-800 Mbps with no sweat, and the Compute Module 4 can do 940+ Mbps assuming you use a PCI Express NIC instead of using a USB 3.0-to-Gigabit NIC.

I had to do this as part of my testing of two new Compute Module 4-based router boards, both of which may make some decent low-cost and tiny Gigabit routers / firewalls / VPN appliances, depending on your needs.