I’ve since realized that Hugo’s architecture provides a variety of template optimization strategies. Hugo builds pages concurrently, so it might be hard to see on a modern device but before partialCaches or module mount trickery — there’s still the implicit complexity of the output/lookup model.
Generally the complexity cost of the default output formats are: page > term > taxonomy > section > home. Keeping expensive calls inside a section and/or a home template is usually optimal. i/o and maybe memory should be the only problems with lots of pages.