It used to be that holding SHIFT and using the mouse wheel increased the scroll speed, and holding CMD changed scroll direction.

Now, holding SHIFT increases scroll speed direction AND changes scroll direction, while CMD still changes the scroll speed.

This means that, previous to the update, if you were scrolling veritcally down your document, you'd scroll normally, and could then hold shift to increase the speed. Whereas now, if you want to increase the scroll speed without changing direction you have to hold CMD as well.

IE - Previously used to work like this:

Scroll Wheel = Vertical Scroll
Scroll Wheel + CMD = Horizontal Scroll
Speed up Scroll = Add SHIFT (ie Horizontal scroll still requires CMD)

Now it works like this:

Scroll Wheel = Vertical Scroll
Scroll Wheel + CMD = Horizontal Scroll
Speed up Vertical Scroll = Hold CMD SHIFT
Speed up Horizontal Scroll = Hold SHIFT (with no other shortcuts).

This makes NO sense!