xcode 5, Mountain Lion: Very slow performance

Question

Installed Mountain Lion and Xcode5. Tried to open a project recently developed for iOS6. And now xcode is dramatically slow. Any ideas whats wrong with him now?

EDIT

It works fast with new projects I create. It slows down only when I open the old projects.

Answer 1

Ok. I found the problem. The screen attached.

When I switch 'Opens in' to Default 5, Xcode changes the UI Presentations to ugly iOS7 design and xcode suddenly starts work fast like in good old times. Switching back to 4.5 brings the very slow performance back. Thats it guys!

Answer 2

It reminds a problem I had with xcode 5 ( also mountain lion), the typing was very slow.. what help to fix this was removing all breakpoints ( I had nice and big list of breakpoints)