Si Unity begins to behave like erratic or slow way we will probably want to restart the shell, which can be easily done by pressing Alt + F2 and running the command
unity
.
Another option to restart Unity is to open a terminal and enter:
setsid unity
O well:
unity --replace &
By adding
&
at the end of the command we will make sure that Unity does not end when we close our console, otherwise when we do we will run out of shell. If it ends anyway then the best thing to do is run the command
unity --replace
using the Alt + F2 key combination.
Sometimes restart Unity it won't be enough for make it work right Again, in this case there is no other option but to close our session and start it again to continue working without any burden.
More information - Unity: Using the new launcher design in Ubuntu 12.10, Accelerating Unity on modest systems