API:Caching data

The Cache-Control header
To fix: When does MediaWiki sets the Cache-Control header, and what does its value mean?

Javascript and local cache
To fix: Which clients can set up a local cache, and which can't (Javascript)

Improving cache hit ratio
To fix: How to normalize web service URLs to get more cache hits (eg. sort page titles so Foo|Bar isn't a different URL from Bar|Foo)