Training and inference timing benchmarks for Chemprop can be found in Tables S12, S13, and S14. These benchmarks were measured on three systems: a compute cluster node with CPU only, a compute cluster node with a GPU resource, and a laptop. We used an Intel Xeon Platinum 8260 processor (2.4 GHz, 48 CPU cores) for cluster CPU benchmarks and an Intel Xeon Gold 6248 (2.5 GHz, 40 CPU cores) processor with an Nvidia Volta V100 GPU for the cluster GPU benchmark timing. Both devices are part of the MIT Supercloud. For both systems, we restricted the maximum numbers of CPU cores accessible to Chemprop to 8. For laptop timing, we used a Thinkpad X1 Carbon with an Intel Core i7-1280P (1.8