For average everyday tasks of the average everyday user, not much.....although it will give you a small overall performance boost in general terms.
However, if you will be regularly using apps that are either CPU or ram-intensive (or both), you will notice a fairly significant difference in their performance. That is a 50% increase in bus speed after all, and apps that rely on lots of data moving from the cpu to the ram & back will be able to do it in a much more efficient manner........