The macb ethernet driver (Raspberry Pi 5) delivers interrupts only to the first core, quickly saturating it at higher packet rates. Introducing software interrupt coalescing dramatically alleviates this limitation; the oneliner fix is upstream at d57f7b45945ac0517ff8ea50655f00db6e8d637c. Please backport this fix to 6.6 -stable to bring this benefit to more Raspberry Pis; it applies cleanly on this branch. Many thanks, Daniel -- Daniel J Blueman