as the primary workhorse for model specification and numerical optimization. We also provide limited support for OpenMx.65 To run the multivariable LDSC function on five phenotypes takes ~15 minutes, a step in the analyses that only needs to be performed once. For models of multivariate genetic architecture that do not incorporate individual SNP effects, the typical run time observed for 3–15 traits is <1 second on a standard personal computer. Using parallel processing implemented in the GenomicSEM package on a 4-core/8-thread laptop, a multivariate Genomic SEM GWAS with five indicators and ~1 million SNPs took ~8 hours. With the time needed to run the models will increase with increasing model complexity, and with increasing numbers of variables or SNPs. In these cases, computing time can be greatly reduced by using a computing cluster to distribute SNP models across nodes/cores.
