A nice short article well worth reading ...
https://www.petzl.com/US/en/Sport/News/2016-10-12/Alpinism--what-does-%22Fast-And-Light%22-really-mean-#.WAoib5OLRAY?utm_source=facebook.com&utm_medium=petzl-page&utm_campaign=Alpinism--what-does-%22Fast-And-Light%22-really-mean-&utm_content=en