One of the often overlooked features of Safari is its Activity window, hiding in plain sight in the Window menu (or just press Command-Option-A for fast access). The Activity window shows activity related to the Web pages you are viewing. If you try to load a page and it stalls out with “loading,” for instance, the Activity window will show you exactly which item is causing the problem—just click the disclosure triangle next to the page in question, and you’ll see entries for every item on the page, and (if those items are loaded) their size or (if they’re not loaded) a message showing their status.