From version 1.0.6, We have introduce a global cache variable that can handle from ExpressionEngine's config.php file. Default cache is set to yes. You can change to disable cache. By default, if you add an entry in link field, it fires around 10 queries to generate URL. Most of query is from EE side. By caching, We cache the link metadata on first load and after that, all links load from cache instead of firing more queries.
Cache busting is pretty simple to. On save of any entry, all cache for link field is purged for entry. Same for user and category. We also gave a setting to purge cache in plugin's backend.
$config['link_field_cache'] = 'y'; // Enable cache [default] $config['link_field_cache'] = 'n'; // Disable cache