openmpt_module_get_*_name functions return individual item names, but use the C++ APIs that return entire vectors of items under the hood to retrieve the item name. Listing for example all sample names thus introduces quadratic complexity.

The internal implementation (mod->impl) should probably offer both single-name and multi-name variants for the the C++ and C APIs to use, with the multi-name variant using the single-name variant under the hood to avoid inconsistencies in string conversion etc.