Hi!
Sometimes when I run my game it freezes for about ~200 ms every ~600 ms. Deleting
while (window.pollEvent(event))
fixes the problem. The problem isn't present everytime. Sometimes when I run my game it works normal. If the problem appears I usually run the game(or any other SFML application!) as administrator and this fixes the problem.
My system is Windows 8.1 Pro and I use Visual Studio 2013 for Windows Desktop.
Sorry for bad english!