If you're using a laptop, Vista, and a wacom Vista by default treats the laptop as a TabletPC. One of the things this does is interprets a pen "press and hold" as a right-click. This conflicts with CS4's zoom tool when you "press and hold" by causing a delay before you get the smooth opengl zoom.
If you like fast smooth opengl zooms by pressing and holding then you can turn off this feature in Vista Control Panel > Hardware and Sound > Pen and Input Devices.
In the first tab (Pen Options) double click on "Press and Hold" and then
turn off "Enable press and hold for right clicking".
Now you don't get that stupid delay whenever you press and hold the pen. Hope this helps cause this was really aggravating me until I just figured it out today.