But it consists a lot of things which may or may not be required to a particular user. In that case you can install a Window Manger instead of a Desktop Environment. A window manager is simple, it’s work is just to manage windows. The download and install size is also very small. But that also means that you will have to install everything on your own, and also set up things like a lock mechanism and notification system yourself. The basic productivity rule is hide everything unused, except what is used constantly. GNOME 3 hides everything, so it is like that if every time you stopped using your pen in class you put it into your backpack.
Moreover its graphic performance is just ugly in nearly any case. Responsiveness of an interface is critical, and GNOME 3 makes jumps when typing even in many of the greatest computers. The lag is usually very obvious. But the ending problem is that these things exhibits a lack of leadership. Specially when their developers insisted in continuing all the way, removing everything about the previous GNOME. This shows lack of idea about how to innovate a product, how to fit the product to users needs, or what makes libre software great. Bottom line, as a good friend says, all together are smarter than any of us. And leadership is knowing how to take advantage of that, to give form to all that knowledge into one product. For that you need to be concious that any opinion about how things should be done could be proven wrong any time by any new small detail, so you will be willing to get those details from others.