from my brief search:

real-world OPNsense (yea, that's not Debian) benchmarks show that even low-power Xeon-D (Skylake-D SoC) with 10G SFP+ NICs:

pushed 9.40 Gbps in plain router mode

7 Gbps with packet filtering and no rules

7 Gbps in NAT mode

5.5 Gbps with a default ruleset