The settings that made the most difference for me, runnning opnsense bare metal :
In the bios :
PCH-IO > PCIe Config > Root Ports 1,4,5,6,7,8 > ASPM = Auto
In the opnsense tunables :
hw.acpi.cpu.cx_lowest = C3 (enables C3 C-states)
Then you can also limit the CPU clock speed with P-states. I...