With TSO and GRO, the CPU deals with jumbo frames and the NIC handles splitting and combining them. You are correct that intermediate boxes all take a perf hit

With TSO and GRO, the CPU deals with jumbo frames and the NIC handles splitting and combining them. You are correct that intermediate boxes all take a perf hit for the extra packets, because routers and other boxes are usually packets per second bound at some point, rather than bandwidth.