Users may periodically experience problems under Mac OS X wherein they start experiencing choppiness or other unexpected slowdowns in applications. This might be particularly true when the programs are handling files or other data, such as loading files from disk or streaming video from the Internet.
Apple Discussions poster BobInIndy1:
"I want to watch videos over the web, but have found that difficult. The main problem is constant buffering. It will play 2 seconds of video and then buffer, making it unwatchable. This is both connect via Ethernet or wireless, using a high speed cable modem."
When many programs load files or other content, they will store commonly used items in an easy-to-access location called a "cache". The system provides a system-level cache, a global user cache, and a local user cache, each of which can be the location used for temporary data. For most user-run applications, however, the local user cache in the user's library folder (/username/Library/Caches/) will be used.
If these cache files become corrupted (which can happen quite frequently), the programs accessing the corrupted cache may experience loading problems. The cache files are just temporary files, and as such are replaceable so if users are finding odd slowdowns occurring, it is recommended to clear the caches in the system. This can be done either manually, or preferably through a utility program such as OnyX, Leopard Cache Cleaner, or Cocktail.
Clean caches through a third-party utility Download and run one of the following utilities, or search for a leopard-compatible cache cleaner at http://www.versiontracker.com.
Clear the problematic cache manually To clear the cache manually, go to the /username/Library/Caches/ folder and locate the file that's associated with the program that's running slow. For instance, if Safari seems bogged down, locate and remove the "com.apple.safari" file in the cache folder. These files are most likely in the user's library, but they may also be in the /Macintosh HD/Library/Caches/ folder as well. If users cannot locate the proper cache file, all the files in the Caches folders can be removed.