I think the paper has what you are looking for. Several figures comparing performance to HRES, and "GraphCast... took roughly four weeks on 32 Cloud TPU v4 devi

I think the paper has what you are looking for. Several figures comparing performance to HRES, and "GraphCast... took roughly four weeks on 32 Cloud TPU v4 devices using batch parallelism. See supplementary materials section 4 for further training details."