In case you don’t use htop already better install it since it displays individual core utilization. By default regardless of IRQ affinity all IRQs are processed by cpu0 so without manually tweaking IRQ affinity you get pretty fast bottlenecked by CPU: https://github.com/armbian/build/blob/master/scripts/armhwinfo#L217
On a related note: How fast do CPU cores clock in your installation: /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
Cpufreq scaling should scale between 800 and 1200 MHz but at least the Armbian dev currently working on Espressobin reports the CPU cores being limited to 800 MHz for whatever reasons (by examining the .dtsi I wondered that OPP for dvfs/cpufreq scaling are currently missing but I didn’t had a closer look).
The older Armada 38x SoCs (Cortex-A9 and clocking up to 1.6GHz) are known to saturate a 2.5GbE link so there’s still some hope 😉
