My favorite, and really useful for batch processing scripts, is `--expose-gc` which allows you to use `global.gc()` in your processing script after each item (or N items), keeping your total memory use lower. It's not a good thing for service processes (generally), but for long-running workers, can keep you from experiencing large GCs in the middle of the run, or from inflating the memory use on a system that's shared for other processing scripts.