It's also likely that the network connection between the user and the cache will be a higher-performance line than the connection between the user and the server, so data is transferred faster from cache to user than from server to user. With a cache, items served from the cache won't be fetched from the server via the Internet, so there's less bandwidth used. This leads to cost reductions for Internet connectivity. Accessing content from a nearby cached copy is cheaper than reaching across the Internet for the content. These benefits typically accrue as companies move to an intelligent content distribution optimization strategy that relocates content closer to users.
Productivity is probably the most difficult benefit to measure.
Service quality is also difficult to measure, although surveys can be used to address customer-satisfaction issues. Filtering is a proven use of cache. Performance is also a fairly well-tested measure for cache, though there's some debate about the benchmarks and how to measure them. There's a key gap in the caching arena that's slowly being addressed. Many caching vendors supply only a specific caching product.