I upteaded my dexpot recently and now I have this same problem.
The switching desktops was instantaneous but now it takes 3-6 seconds to switch. I have 3 desktops and when I go through them all then the new round will be quicker but not as quick as it was earlier. Then it will take some time and the switching is back to very slow again.
There was a new version 1.6.0 Build 2101-RC which I installed. Lets see will this give any help. I have that log file for you but I will send it to you by email (contains some private information). But I give this a try and if the problem still exists I will send the log for you.