The scalability of the SMIRNOFF parameterization process is summarized in Figure for all systems. A variety of large protein systems up to 42,392 atoms were used to benchmark loading for large biopolymer systems, and additional homopolymer systems were built by copying ∼1000-atom polymers to create systems up to 81,810 atoms (the size of the largest system reported in Table ), as PDB atom coordinate limitations prevented construction of single long molecules of that size. All small systems of less than 2000 atoms could be parameterized in less than 10 seconds, while larger systems could take up to 10 minutes to parameterize. Assignment of parameters given chemical information, existing functionality within the Open Force Field toolkit, was the time-limiting step in the file-to-simulation workflow. System loading and assigning chemical information with monomer templates could be completed in about 20 seconds on average for very large systems. In the OpenFF toolkit, parameterization involves many more SMIRNOFF parameter subqueries to be performed across all valence and non-bonded parameters compared to the querying process for monomer templates. Because of this, system loading from PDB is scalable within the OpenFF toolkit.