Date: 2002-09-12 Docket: 02-46 David Loukidelis, Information and Privacy Commissioner. | Link
"This is called "caching"; each computer stores and preserves images locally that may be wanted again. Using the readily accessible local copy prevents reloading the image from a remote (and slow) source. Unix and Windows operating systems routinely cache images, as do individual web browsers.

Date: 2004-06-30 Docket: 29286 Binnie J for the majority opinion. | Link 

"The practice of creating "caches" of data speeds up the transmission and lowers the cost. The subsequent end user may have no idea that it is not getting the information directly from the original Web site. Cache copies are not retained for long periods of time since, if the original files change, users will get out-of-date information." (para 23)