If it's not possible then maybe just the Dash show/hide animations. I simply find myself waiting for animations which is pointless.
1. Why you cannot disable this Dash animation in Unity 12.04
2. Alternative A: Switch to Ubuntu 2D
Ubuntu 2D has different Unity Shell code, and there, launching the dash via Super is instantaneous and does not animate anything.
3. Alternative B: Use a custom shortcut to launch the Dash by clicking on the Ubuntu Logo, thus bypassing the animation
We can exploit the fact that the opacity/fade animation does not happen when you launch the Dash via the "start" button, or, if your cursor is on/around the launcher bar, even if you press Super:
The animation will be delayed until your cursor actually moves inside the dash area.
Install Compiz Configuration Manager.
Ubuntu Software Center: Compiz Configuration Manager
Once installed open it and got to
From there you can set
If you want, you can change the panel and dash transparency to be full opaque.
Sorry, You can't. At this point (25th July, 2012) with Ubuntu 12.04 LTS, There is NO easy way to disable Unity animations. (at least without recompilation).
And I don't think, there will be an option to disable animations in future releases. Because, One of the goal of Unity is to provide pleasing user experience and animations are considered one of the best way to achieve that.
The possible workaround for you is changing the dash animation to fade (cause, In my opinion, fades are quicker than sliding). You may also interested in disabling the animations for all windows also. To do this,
If you want to disable the animations in all window, you can disable the Animations plugin in ccsm. If you want to disable Fading, disable the Fading windows plugins.
Hope this will help.
Edit: As izx showed in his edited answer You clearly see that, the options of dash animations are hard coded in the Unity, and those cannot be changed with any configuration options, because those time durations aren't variable which can be changed. So, this means, You have to recompile unity by changing those time durations to 0 ms to completely disable the animations.
To add to Ángel Araya's instructions: I was able to disable all animations by deselecting
I think turning off fading-windows under effects in CompizConfig Settings Manager can make a difference in Unity. (A subtle difference in speed, but still a difference.)