CPU is never a real issue in my experience, even when using compression (lz4) on everything. I do run an 8-core machine, but it's only a Intel Avoton C2750 (ASRock C2750D4I is pretty cool motherboard board with 12 SATA ports built-in), but I do have 32Gb ECC RAM. 16 was probably enough, but I run other things on it in Docker (Plex media server etc). I installed a plain Ubuntu 16.04 with ZoL - and it has been rock-solid.