And because there are fewer service delays between a cache and a browser, a cache increases the transmission bandwidth to the browser for cached objects. With a streaming media object, for example, a cache detecting a 1 MBit connection to a browser will serve the media to the browser at that speed. On the other hand, a media server located across the country would detect less available bandwidth for the distance to the browser, and would therefore serve the object at a much slower speed, reducing the quality of the browser user's experience. Caches implemented in diverse geographic locations also minimize the distance that data has to travel, thereby reducing long-distance transmission costs. Caches also help to reduce bandwidth demands during network traffic surges.
Surges occur when a very large group of users wants access to the same small number of pages.
For example, the release of the Starr report in 1998 overwhelmed capacity due to the huge volume of people requesting access to the same objects, causing a network traffic jam that took hours to clear. Surges can swamp any portion of a network, regardless of the network's bandwidth. However, the more users requesting the same objects, the more likely it is that a cache will alleviate the problem. The more users wanting the same object, the more likely it is that the objects will be stored in the cache, and the more effective the cache becomes at eliminating upstream traffic. Caches can completely eliminate upstream traffic surges caused by heavy demand for a few specific objects.