Cycle preferences are only available when Advanced Editing is selected in Advanced preferences.
Cycle Pre-Processing pop-up menu: Processes a cycle jump slightly before its actual position, in order to ensure a smooth cycle jump from the end point to the start point of the cycle. You can change the pre-processing time. A value of 1/96 (chosen by default) should be suitable for most uses.
Smooth Cycle Algorithm checkbox: Improves the timing of cycle jumps, making it easier to set the length of sample loops while in Cycle mode. This is somewhat mitigated through the use of Apple Loops. If your computer has a very slow processor, this setting reduces the processing requirements for graphics operations. In general, you want to keep this selected whenever possible, especially if you’re working in a style that involves frequent cycling of musical sections. If you find that your cycled sections are not as smooth as you’d like (assuming that your loops are actually perfect), you might achieve better results by deselecting this checkbox.