How would you make a faster Firebrick model that could route more than 1 Gbps? Faster clock speed? New processor that can do ILP, ie. more instructions per clock cycle and/or has a reduced clock cycle count for critical instructions, i such is available.
Or using offload hardware: something that can parse IPv4 and IPv6 headers? CAM? Something that can help with the longest prefix match algorithm? With the latter of such hardware, I worry about what happens when that hardware runs out of (its own) RAM; say an attack fills all the off-CPU RAM up with junk. I don’t know anything at all about router design. If I were designing a router, I would have to rely on software, so I would just pick a ridiculously fast CPU and fast RAM, write highly optimised code and hope, which isn’t good enough.