I am fan of Xubuntu just because of its snappiness. Now i know that it is based on light-weight XFCE which is the secret for this snappiness but I am just wondering if something could be done on Unity to bring it, say, close to that snappiness?
I have not installed NVIDIA's driver as I have never seen any improvements on Ubuntu. Would love to hear views on this in case somebody have been able to tweak some settings.
Obviously you computer struggles a little with full Unity.
Try Ubuntu 2D (click the gear icon on the login screen). It's almost the same, and a snappier on lesser hardware.
The short answer is No. The existence of environments such as Xfce and LXDE is not by accident. They appeared out of needs - main of them being less resource usage i.e. better performance at less resources available.
Issue No. 2 - inherent Unity flaw:
It uses long animations - Unity at its best will feel 'smooth' but never 'super fast' Unlike many people say animations for main Unity elements like Dash cannot be disabled: How to disable all Unity animations?
Issue No. 3 - bugs in Unity:
I can't judge whether it has more bugs than other environments or shells but there are some issues in Unity that degrade overall experience e.g. Dash maximized opens up twice as long as Dash at standard size, see https://askubuntu.com/a/169634/29347 Since Unity relays on Compiz as another layer, I'd say it's even more prone to bugs.
My personal recommendation for those with modest rigs or even those with modern hardware but not wanting to 'wait for animations to finish': Lubuntu (with LXDE)
http://www.phoronix.com/scan.php?page=article&item=linux_desktop_vitals&num=1
On a side note: Unity as well as GNOME cause gaming performance degradation. These two I know of. Try digging on phoronix.com a little.
On my machine, installing the nvidia drivers increased the unity performances quite a lot, from unusable to usable.
Unity runs fine on my deskop and laptop, only in my small AMD APU C50 it feels laggy and there I use Xubuntu 12.04LTS but bear in mind, Xubuntu and Lubuntu has plenty of crashes, nothing serious but just live with them. Also Lubuntu however good it may sound doesn't have automount etc. the convenience of Ubuntu Unity is a small price to pay in most sense if your hardware can run it.