Just a little rant!
I've been dealing with this since upgrading to 2.5.
Honesty, in that gif I was going pretty wild but no matter how slow and accurate I go the result is the same, it takes a while to open it or close it.
Not to mention, but it could be a problem from my side, that if I remove a text widget all the content gets deleted, I used to move around text widgets from one sidebar to another but now I have to open it (if I'm lucky in a couple of clicks) copy the content, close the widget, display the other sidebar, add a text widget and paste the content from the other one.
That's not good!