Manual:$wgCachePages

Cache: $wgCachePages
Allow client-side caching of pages
Introduced in version:before 1.1.0
Removed in version:still in use
Allowed values:(boolean)
Default value:true

Details edit

Allow client-side caching of pages. If $wgCachePages is true, MediaWiki will check the $_SERVER["HTTP_IF_MODIFIED_SINCE"] of the request and MediaWiki will respond with 304 Not Modified, if the page had not been modified since the last time it got requested.