The process that takes by far the longest is triangulation. So you can save yourself a ton of processing time by triangulating a mesh before import in a dcc.
by contrast, generating lightmaps is not an intensive. However disabling the option and always making the lightmap on the 3d program saves import time as well.
Other than those 2 things, there isn’t much else to be done. Perhaps use Alembic for intense geometry morning, since its kind of what it was built for.