For 13.04 I it would be better if there was a certain effort put just into reducing the system requirements of Unity and also making it faster on slower machines. The problem is none of the developers of Unity or the desktop team generally have computers that are "slow" for example a netbook or similar systems which they have to use daily.
Now that unity-2d is gone, its really important that unity (we can say Ubuntu since unity is part of Ubuntu) should be much quicker on low end system. For example I have a netbook that have Intel Atom 570 (has opengl 1.4) and opening the dash takes 1sec which is very slow IMO. The minimize a window as well is very slow.
In my testing Unity is quite fast and responsive on opengl v2 intel GPUs, it flies on My SandyBridge laptop but I have found it to be not-that-quick on Nvidia even on a very powerful GPU such as 9800GTX+ (I consider it powerful for a desktop environment atleast).
So I think in R cycle finding performance issues just in unity and fixing them would be a great thing for Ubuntu. Else it may make sense to consider adding Opengl v2 as a recommended system requirement to install Ubuntu so that people are warned.
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