Can hitting the ball to hard cause a slice?

I find that when i swing too slowly, i hit a big hook. when i try to nail one, it will slice. This may be total bu***t
but my theory is, swinging too fast gives your upper body not enough time to catch up with your lower body,

swinging slower gives you more time to square the clubhead at impact. P.S this information is not to be trusted, it's just how it felt to me when i struggled with a slice.