An id parameter can (optionally) be specified to uniquely identify a cache macro on a page. If specified, this can improve performance when doing previews and macro browser previews by reducing the number of cache refreshes needed. An explicit id means that a single cache entry can be used as you move between view, full edit preview, and macro browser preview. Of course, if you make an actual change in the macro browser, the cache will need to be refreshed, but normally only once in the cycle between macro browser refresh, preview, and actual showing the page. | 
