Whether you've installed Ubuntu on an older computer or you're rocking a low-powered netbook with Ubuntu installed, Ubuntu's Unity interface can be a little sluggish. Unity 2D is a low-resource version of Unity designed for weaker systems.
Ubuntu Unity is one of the coolest new features of Ubuntu 10.10 Netbook Edition (and all editions of the upcoming 11.04), but if you find it lags a bit too much for your tastes, the low-resource Unity 2D should make you a bit happier. It's currently in the daily build stages, but apart from a small quirk or two (like the rearranging of dock icons being broken), I found that it runs significantly faster than the default Unity installation. The only real difference is a lack of 3D eye candy. You can install it in either Ubuntu 10.10 and 11.04 by running the following Terminal commands:
sudo add-apt-repository ppa:unity-2d-team/unity-2d-daily sudo apt-get update sudo apt-get install unity-qt-default-settings
This will add the PPA to your system and install the correct package. Afterwards, log out of Ubuntu and you'll find you can pick Unity Qt instead of the Ubuntu Desktop or Netbook edition when you log back in. If you've got a low powered computer, give it a go and let us know how you like it in the comments.
Unity 2D (Qt) Now Available in a PPA For Ubuntu 10.10 and 11.04 [Web Upd8 via Download Squad]