Ubuntu – Unity menu very slow and unresponsive

Why are you wondering that a computer with an old graphics card and 2GB of slow RAM can't run a desktop with effects enabled?

I would say you need reflect here on what are you needs and what you would like to see happening depending on you definition of really slow and when that happens.

• Test your hard disk for speeds and access time, a slow hard drive will make the results on the dash hard to load and that might slow down accessing it;

• Create a file (or edit a present one) in you home folder with the name .xprofile with your favourite text editor, ie: nano ~/.xprofile and add

  export UNITY_LOW_GFX_MODE=1

  This will load Unity without the special effects that it normally uses making it more responsive

• Test another desktop environment, XFCE and LXDE are much littler on effects and would speed up computer usage and tasking in your case.

For a more complete list and comparison of different desktop environments and shells please have a look at What kinds of desktop environments and shells are available?

It will help decide and install a different desktop environment on your system, consider any of the following first: XFCE, LXDE or GNOME Classic.