I have upgraded from Ubuntu 12.10 to 13.04. After upgrade when I open nautilus it takes around 10 seconds to respond to my click, for example when double clicking a folder to open it then it works fine and when trying to close nautilus it takes around 6 seconds after I click the "x" button to get closed.
Also when my laptop starts up when trying to mark up folder on my desktop using the mouse it lags.
I have Ubuntu installed on Sony Vaio SVS13125CAW with 2.5GHz i5 processor with 3MB Cache, 4GB RAM and 5400 rpm disk.
Here is a YouTube video showing the lag, http://www.youtube.com/watch?v=JUd0Hy5Acb8