Starting with SMW 1.8.0, Semantic MediaWiki introduces an user preference tab in the My preferences section (see here) where options are available to enhance the SMW experience by allowing customization on a per user basis.
This option allows to fetch content updates automatically during a page refresh (or initial page load).
Local storage (part of most modern HTML5 web browser) is a browser storage engine that allows external content provider (which in our case is the result printer) to store arbitrary information that can help improve response time. One current application is in order to decrease necessary ajax calls, the local storage keeps information about an image/thumbnail location within the browser cache so that the next time the same image is requested this information (url etc.) is recalled from the browser instead of asking the server again.
The local cache time is set to 24h for an individual item, after that the browser will initiate a new request. The local storage can be deleted at any time and will not influence the behaviour or functionality of the result printer.
Setting default values
See $wgDefaultUserOptions for how to set default user preferences for anonymous visitors and users who did not set a preference themselves. For example extent the "LocalSettings.php" file with an inclusion of Semantic MediaWiki and Semantic Result Formats:
$wgDefaultUserOptions['name-of-the-user-preference'] = 1;
Help:User preferences en 1.8.0