Serious Lag Issues

Hello, I have encountered serious lag issues recently in my games. For example, when I move a stack, it takes over a minute sometimes to show that it is moving. This also applies to construction or producing new units or starting research. What's funny is that it does not happen all the time, I would say once every four or five actions I make there is a lag issue. I am playing from the same PC so I don't think it's anything I did.