Comment by milch

Depending on the CLI tool you could even forego memory management completely and just rely on the OS to clean up. If your program completely reads arbitrary files into memory it's probably not the best idea, but otherwise it can be a valid option. This is likely at least partly what happens when you run a benchmark like this - the C++ one cleans everything up nicely if you use smart pointers or manual memory management, while the Java tool doesn't even get to run GC at all, or if it does it only cleans up a percentage of the objects instead of all of them.