A clarification : Gnome is a Desktop Environment Management System. Gnome will allow this like Window mangers to be used, like Openbox, ...etc.

Gnome is defined as " GNOME (pronounced /ɡˈnoʊm/, or sometimes /noʊm/)[1][2] is a desktop environment / graphical user interface that runs on top of a computer operating system. It is composed entirely of free and open source software and was created by two Mexican programmers, Miguel de Icaza and Federico Mena. It is an international project that includes creating software development frameworks, selecting application software for the desktop, and working on the programs that manage application launching, file handling, and window and task management."
http://en.wikipedia.org/wiki/GNOME

A window manger is, "A window manager is system software that controls the placement and appearance of windows within a windowing system in a graphical user interface.[1] Most window managers are designed to help provide a desktop environment. They work in conjunction with the underlying graphical system which provides required functionality such as support for graphics hardware, pointing devices, and a keyboard, and are often written and created using a widget toolkit.[2]
Few window managers are designed with a clear distinction between the windowing system and the window manager. Every graphical user interface which uses a windows metaphor has some form of window management; however, in practice, the elements of this functionality vary greatly.[3] The elements usually associated with window managers are those which allow the user to open, close, minimize, maximize, move, resize, and keep track of running windows, including window decorators. Many window managers also come with various utilities and features: e.g. docks, task bars, program launchers, desktop icons, and wallpaper."
http://en.wikipedia.org/wiki/Window_managers\

I would as read the rest of the Wiki  about window mangers.

What is Compiz ?
(taken from Compiz README)

Compiz is an OpenGL compositing manager that use GLX_EXT_texture_from_pixmap for binding redirected top-level windows to texture objects. It has a flexible plug-in system and it is designed to run well on most graphics hardware.

Okay, this description isn’t really meaningful. In a nutshell, Compiz is a compositing manager, which means that it enhances the overall user interaction by adding fancy effects to your windows, from drop shadows to awesome desktop effects like the Desktop Cube or the Expo view.
Compiz can also be a window manager, which means that it is the software between you and your desktop apps. It enables you to move or resize windows, to switch workspaces, to switch windows easily (using alt-tab or so), and so on.

If you heard of Beryl or Compiz Fusion, it’s us as well ! Check the wiki page for more details on the (somewhat troubled) project history.

The latest release of Compiz is 0.8.6. A C++ rewrite has been announced on 24th December 2009 and is about (June 2010) to be released as a beta version. This is a major rework of the whole project, aimed at easing future development.

What was Compiz Fusion ?
(taken from AboutCompizFusion Wiki page)

Compiz Fusion is the result of a merge between the well-known Beryl composite window manager and Compiz Extras, a community set of improvements to the Compiz composite window manager. Compiz Fusion aims to provide an easy and fun-to-use windowed environment, allowing use of the graphics hardware to render each individual window and the entire screen, to provide some impressive effects, speed and usefulness. The first Compiz Fusion developer release was Compiz Fusion 0.5.2 on August 13th 2007, shortly after Compiz 0.5.2 was released. First stable release of Compiz Fusion is 0.6.0 released on October 20 2007.

and form the forums.

Re: Compiz Addons: A script to install experimental plugins
... and they work wonderfully. Now ubuntu 11.04 is upon us (and congratulations to the Compiz team for the important role it plays in developing the Unity desktop), I am wondering if these dazzling plugins will be updated and made available in future releases of Ubuntu. I have tried to install them ...
by soreau
Sun Mar 20, 2011 4:33 pm

Forum: Guides and FAQs
Topic: Compiz Addons: A script to install experimental plugins
Replies: 48
Views: 21766

"...Developers will be able to create extra ‘places’ for users to add to the ‘Dash’ and multi-touch functionality to the shell as a whole will be introduced using the uTouch framework.

Notably, Desktop Unity will use Compiz rather than Mutter for compositing.

GNOME
"Unity is a shell for GNOME – it may not be GNOME-Shell but it is a shell for GNOME." Shuttleworth told the audience on the potentially contentious issue of this move being seen as moving away from GNOME.

"It’s healthy for GNOME for to have competition." he went on to say before iterating that developers are ‘in this together’...."

http://www.omgubuntu.co.uk/2010/10/ubuntu-11-04-unity-default-desktop/

Cheers.

I guess I said it  Unity is a Compiz plug in.  I Yeah ad to brake it to figure that one out. So its a Plugin.......   So.... It going to use more system resources, simple because its not a native to Gnome, it is native to Compiz.   So... Just change your session  to "the classic Ubuntu"  done.

I guess Wikileaks does have to leak out government docs. One more thing...." The British music industry has called for a truce with the technology firms with whom it has till now fought a bitter battle over rights, royalties and file sharing.

Feargal Sharkey, CEO of lobby group UK Music, told a conference in London this week that it was time for the music and technology industries to set aside their differences and strive instead toward a common goal: nothing less than the total global domination of British music.

Sharkey, a campaigner against people copying music on the internet and the technology they use, said it had become apparent that technology and creativity were inseparable.

"It's now time for ISPs and tech companies to sit down together and possibly for the first time have a broad adult conversation. Our future is now totally dependent, totally entwined, totally symbiotic," he told an audience of industry, government and media at the Westminster Forum this morning....."

http://www.thinq.co.uk/2010/9/4/uk-music-calls-truce-technology/
Sharkey was on rousing form. The former pop star called dramatically for the mobilization of British music and technology producers: "By 2020. We. Want. To rival. The United States. As the largest. Source of repertoire. And artistry. In. The. World."

http://spectrum.ieee.org/aug07/5429 "You're listening to your favorite Pink Floyd CD on your home stereo when you accidentally hit the âoechange CDâ button on the control panel. All goes quiet for a bit as your CD player urgently shifts to play whatever is in the next tray. With dread, you desperately reach for the volume knob, but it's too lateâ"your speakers blast the latest Green Day album. Reacting like you were just pricked by a pin, your hand jolts to the volume knob and turns it down. You breathe a sigh of relief. But that's not the end of it. Ten minutes later you feel that something isn't right. Even though you love this album, you can't listen to it anymore. You shut it off, tired, puzzled, and confused. This always seems to happen when you switch from a classic album to a modern one. What you've just experienced is something called overcompression of the dynamic range. Welcome to the loudness war. The loudness war, what many audiophiles refer to as an assault on music (and ears), has been an open secret of the recording industry for nearly the past two decades and has garnered more attention in recent years as CDs have pushed the limits of loudness thanks to advances in digital technology. The âoewarâ refers to the competition among record companies to make louder and louder albums. But the loudness war could be doing more than simply pumping up the volume and angering aficionadosâ"it could be responsible for halting technological advances in sound quality for years to come. read more at The Future of Music Continued"

This what i believe is what the truth. Read all of it do not scan it!