I doubt an app would speed it up. If it’s slow it’s probably your site, either server or site itself (due to add-ons etc).
Best advantages of an app are probably push notifications and potentially increased activity (I’d be more inclined to browse a site with an app, compared to having to navigate to its page). Correct use of Safari bookmarks kinda helps with the second issue. Neither seem worth the extensive work of making an app.
This has been suggested and discussed many times before - worth using search before making a new thread.