They've updated the layout, now the entire window is a player with UI overlayed when you move your mouse. On a full HD laptop using Firefox I get over 40% CPU usage, but if I make the window half size I get about 20% - don't remember having this problem when watching the French Open.
http://i.imgur.com/DCn1xz4.jpg
At least it still works and we'll see what happens in a few hours.