World freezing

Everytime i try to type of use a sign i freeze and have to use cntrl alt delete to get out of it, any ideas what could be wrong?

I place the sign and start typing and it gets so laggy when i type that i have to use cntrl alt delete.
I just started the world last night so i doubt its corrupted. I think it might just be something with 1.8 itself.
And yes i can place