Side effects of System cache cleaning

There are several important considerations to be aware of before performing a System-level cache cleaning. These should not dissuade you from using System-level cache cleaning due to the number of problems it can resolve. However, being aware of these potential side-effects is important.

The first restart after System-level cache cleaning will take longer than normal

Your first restart after performing a System-level cache cleaning will take a bit longer than normal as important System-related cache files are rebuilt.

Notifications to approve previously-approved applications may appear.

Mac OS X includes a security feature to protect users from potentially opening documents that could launch harmful applications, such as malware or spyware. This feature was introduced in Mac OS X 10.4 Tiger® and also applies to Mac OS X 10.3 Panther® and Mac OS X 10.2 Jaguar after installing Apple® "Security Update 2004-06-07".

This change requires that you approve the launch of an application the first time you double-click a document to be opened in that application if you have not previously launched that application directly, such as by double-clicking the application's icon.

Once you have approved the launch of the application, no further alerts for that application will be seen.

However, after performing a System-level cache cleaning, you may again see these alerts for previously-approved applications as a System-level cache cleaning may remove the

com.apple.LaunchServices*.csstore

files in your Computer > Macintosh HD > Library > Caches folder. These files save, among other things, information indicating the applications you have previously approved for launch. Some cache-cleaning utilities retain these files to preserve your list of approved applications, while others remove them as they are saved in a System-related cache folder.

Under Tiger, fonts disabled in Font Book may become enabled.

How fonts disabled in Font Book are handled under Tiger is very different from Panther.

Under Tiger, information concerning fonts disabled by each user is saved in an account-specific cache folder within the Computer > Macintosh HD > Library > Caches > com.apple.ATS folder, aka the /Library/Caches/com.apple.ATS directory.

If your cache-cleaning utility deletes this cache, which is normally considered a System cache, fonts you disabled in Font Book will be enabled when you next restart or log in to your account. If you have disabled hundreds or thousands of fonts with Font Book, having all such fonts enabled could result in slow performance of your Mac.

For additional information, see the "How disabled fonts are handled in Font Book 2.0 under Tiger" section of our "Undoing Font Book" FAQ.