I just did some benchmarks. You can see that the USB pass-through performance impact is there, but it is less than I expected.
| Dell Latitude E5570 | Raspberry Pi 5 | Note | |
|---|---|---|---|
| Host Ethernet | 933 MBit/s | 935 MBit/s | RJ45 host only |
| Host USB RTL8153 | 938 MBit/s | 940 MBit/s | USB 3.0 to Ethernet adapter (RTL8153) host only |
WAN_IF: "hostETH" |
932 MBit/s | 931 MBit/s | Host Ethernet attached to OpenWrt container |
WAN_IF: "usbETH" |
940 MBit/s | 938 MBit/s | RTL8153 USB 3.0 attached to OpenWrt container |
USB_1: "0bda:8153" |
610 MBit/s | 250 MBit/s | RTL8153 USB 3.0 pass-through to OpenWrt container |
Please note that all these benchmarks are pure iperf measurements without firewall/NAT.