Gave my 2017 4k iMac (quad-core 3.0 GHz/16 GB RAM/1TB SSD/Radeon Pro 555 2 GB dedicated graphics) a simple Handbrake conversion. It took 31.5 minutes. The same video with the same conversion parameters was done in 13.3 minutes on the M1 MacBook Air (7-core GPU/8-coreCPU/8GB Unified Memory/256 GB storage).