If it's the usual OS X animations used when opening and closing applications, then...
> System Preferences > Dock
controls the settings.
If you're looking at some of the other animations that are around OS X, then some details on what you're doing (that's not animated) or looking at could help folks get you to the the settings you're looking for.
This is the OS X settings, and for recent versions. If you're really using the OS 9 classic environment, this doesn't apply.