Dashboard very slow

Within the past few days my dashboard has become unbearably slow. It is a 3 minutes wait time from login to dashboard. Any movements around the dashboard are similarly slow. Agonizing. The part that the user sees is working normally. It is only under the hood that something is wrong.

I have deactivated latest plugins.
I have a private server with unlimited bandwidth.
I have no dashboard plugins.
I even installed beta 3.9, still with no difference.
My host has checked the database server.
I have tested this under FF, IE and Chrome – all the same.

Thoughts? Help!!