Comment 3 for bug 153322

This was also what caused problems on my system. I had number_of_desktops set to 4 as well as hsize set to 4 (probably some setting that was still in there from Feisty). This caused the workspace switcher applet to crash once in a while, and be really slow when clicking on different workspaces (well, actually desktops). Also, when I switched with Ctrl+Alt+left or Ctrl+Alt+Right, the workspace switcher wasn't updated, since I was still on the same desktop.

Having set number_of_desktops to 4, it works again ...