When importing large files, or many files in batch, the current STL importer is slow,
many file types are getting a native importer/exporter now, so a native importer for STL makes sense too.
An alternative solution is to write a new Python importer, but writing a native C or C++ importer will bring better performance.
This is intended to replace the Python importer, an exporter is also planned, better to split into a different patch.