I've never seen Firefox use more memory than Chrome on modern versions. They're pretty on par.

It's far more likely that one of the many addons/extensions you had was the cause.

As for 'Refresh Firefox', it does exactly what it says it does - wipe a lot of your configuration to bring it closer to stock. It's intended as a way to show people new defaults and help clear out old, bloated configs. It shouldn't be used unless you know what you're doing.