The main bottleneck in Tor relays is often the processor’s clock speed. Since Tor does not support multithreading, the best solution is usually to run a separate Tor instance for each core (or thread). Given the cost of electricity, we are looking for hardware that is both power-efficient and cost-effective while still being capable of saturating the available bandwidth. The apu2, although no longer in production, remains an excellent machine, used for years and with stable support for coreboot. The model we are testing has the following specifications:

We want to determine the configuration that best optimizes resource usage, considering that we have access to a full IPv4 subnet and 2.5 Gbit of upload bandwidth.