Oh boy. I have two computers. On one, I upgraded from 12.04 to 12.10, attempting to go to 13.04 with catastrophic results, requiring me basically to install brand new 13.04 onto machine and this worked just fine. This was okay since I had a backup and didn't use this computer that much. (I'm on it now).
Now, on my main computer, I used sudo do-release-upgrade to go from 12.04 to 12.10. This worked well, I guess, but it wasn't my main destination and I didn't stay long. Everything seemed fine, so I inserted the DVD (13.04) I had used on the other machine, chose upgrade existing system and went to bed.
When I awoke, the first thing it told me was that "some programs could not be installed. You will have to reinstall them after reboot."
My first question is can a get a list of these, somehow?
After reboot, I find that everything is just dog slow. I type into the finder and each keystroke takes close to a second to appear in the edit box. Mouse clicks take forever to process.
My second question is I do have a backup, but short of a complete reinstall, is there anything that anyone might be able to suggest here?
My final question: is downgrade a possibility worth consideration?
I should clarify "everything is dog slow". That is not quite true. Once I managed to launch Firefox (It took a while to type "firefox" in the finder box and clicking icons takes forever), input within firefox, both mouse and keyboard is crisp and completely satisfactory. So it seems that the problem is mainly with the Ubuntu gnome desktop and not the graphics card. Also, even within the desktop "tool tips" appear quickly when the mouse moves over their area - it is only mouse clicks and keypresses on the desktop and task bar itself that are problematic.
UPDATE2: I've also found that Right-Click actions on the launcher bar work well. It's only left-clicks and keyboard actions within text boxes owned by the launcher bar, such as the finder, that are slow. In other words: left click on launcher button: wait forever Right click on launcher and choose menu item that opens a window for app: ok
Also: typing Alt-Tab to switch between apps: dog slow again
UPDATE3: Finally got around to trying ansidev's answer below. I rebooted into recovery mode, enabled networking and did the recovery thing. It did not help.
Current status, the system is basically functional, except for Unity. Everything Unity touches is slow. The uppermost button, you wait forever. Any key typed into the edit box for Unity search takes maybe 5 seconds to appear. Alt-Tab is ridiculously slow. Right-clicking on unity buttons is better, for some reason.
This is not the most recent system ever but it should be adequate. It's a 6 year old Dell Inspiron 530 with 4GB of RAM. I have a less powerful system that is running this same version of Ubuntu (installed from scratch) better than this. Things are a little slow on that machine but acceptably so. This is not acceptable, an order of magnitude worse performing.
I suspect a graphics mismatch somewhere or something like that. It's only when it does all that transparency fade-in business (which I could live without, I admit) that I notice the slowness.
Since I have this other computer running all my critical stuff for the time being I'm willing to spend a little time trying to get to the bottom of this one. But I'm not sure how.
Can anyone help or point me to a source where folks knowledgeable in the nitty gritty of Unity are available? Thanks. If not, my only options will be to reinstall from scratch or to find another distro. I don't want to do that, I've been happy with Ubuntu for six years or more, but if the sizzle is going to overwhelm the steak, it's not good. Looking for the best path forward.