Technical Stuff

Address Book keeps the list file in memory, as opposed to reading each record as required from the disk.

Cons:

•The complete list has to be loaded when the program is opened. With 6,000 records, this takes about 6-7 seconds on a Quadra 605. 
•In addition to the memory required to run the program, 65k is required for every hundred records. Thus, for a 6,000 record Address List, you need to set Address Book's Preferred Memory Size to about 5,000k. If your list gets very big, you may either have to split it into smaller lists, or add memory to your Mac.

Pros:

•Extremely fast searching for any text in any field. With 6,000 records, a Command-F search takes only a few seconds on a Quadra 605. The “Goto” function, that is, finding a record by pressing Command-G and typing the name as it appears in the index, is instantaneous.
•Each time you enter a new record or edit the name of an existing record, the list has to be sorted to maintain correct order in the Index window. Even with 6,000 records, this is done in the blink of an eye.
•Minimal hard drive access conserves Powerbook battery charge.

Safety Features

As you enter each record, Address Book saves it in the List file—in case of a power loss or system crash, the newly entered records are not lost. When you next open the list, the new records appear in order. This saving feature does not apply to edited records.

For further protection, select "Save as You Work”. This saves the list file, if there have been any changes since the last save, one minute after any mouse or key activity in Address Book. Under MultiFinder or System 7 this may occur in the background if you have moved to another application. This can be annoying if you have hundreds of records, so you may want to choose to do your own saves from time to time.

You can select Backup at Quit in the preferences, but we recommend instead that you manually backup from the "Save Backup" menu item (under "File" in the Menu Bar) at times when you know the list is good. If you have made temporary changes, then quit Address Book with "Backup at Quit" on, you will overwrite your original list, and you will be unable to recover it. (Save a backup under a different name for extra security).

Conflicts

Some Control Panels and Extensions (small utilities, usually found in the System folder) trap keystrokes and cause them to perform functions other than the ones you anticipated.

One common problem occurs in Address Book’s New Record and Edit windows when a Control Panel or Extension traps the return key, causing a dialog button to be hit rather than providing the line feed Address Book expects. If the Control Panel or Extension does not provide a means to disable this operation, you will have to remove it while you are using Address Book. For example, turn off Dialog Power in the Black Box by Andrew Welch. This problem is not unique to Address Book.

Address Book may not find the path to the prefs and list files with AutoDoubler installed. Turn off AutoDoubler's compression for the Address Book DA and/or application.

If you have other software that uses the serial port, especially fax software, you may sometimes have difficulty dialing the phone with Address Book. Turn off the other software if this happens, or run Jim Leitch's freeware SetClock, which clears the serial port (it also sets the Mac's internal clock by dialing one of several time servers). In extreme cases, you may have to restart the Mac to force the other software to let go of the serial port. 

If you use the other software all the time, you can get around the problem by installing the Desktop Dialer™ from Sophisticated Circuits, which does not use the serial port.