Webpack needs to grab certain settings from LMS and Studio such as the STATIC_ROOT directory.
The python script therefore makes three separate calls to the print_setting management command to grab this information:
python manage.py lms --settings=devstack_docker print_setting STATIC_ROOT 2>/dev/null
python manage.py cms --settings=devstack_docker print_setting STATIC_ROOT 2>/dev/null
python manage.py lms --settings=devstack_docker print_setting WEBPACK_CONFIG_PATH 2>/dev/null
Even though this is basically grabbing three config values, it takes roughly 36 seconds to run on my devstack because of high edx-platform startup costs. This is almost the same amount of time that it takes to actually run Webpack. This cost is incurred whenever you run `paver update_assets`, and accounts for ~13% of that time in dev mode.