The Blender OBJ loader was incredibly inefficient. Blender used something like two orders of magnitude more RAM than necessary, so even a small model would take gigabytes. It was basically useless for any model of even modest complexity. Working around its limitations was dozens of hours of effort when I was importing and rendering my own procedurally-generated models.

I was seriously considering rewriting the Blender OBJ importer myself. Ultimately, I ended up writing an OBJ to Alembic converter, since Blender handled those more efficiently.