Currently complex elements (Like the Grid and the Chart) have so many properties and methods that the page has so many DOM elements it takes forever to load.
While I agree that those pages are large, we prefer to keep the entire API for an object on a single page, so this is by design. That said, We are continually optimizing our documentation to make the content as consumable as possible (ie we added a filter to the header and added menus for all properties and events).