defer loading of feeds until visible (#1271)

* defer loading of feeds until visible

* Fix: use existing hasLoaded

* Fix: dont query for latest during initial load

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

src/view/screens/Home.tsx

@@ -56,7 +56,6 @@ export const HomeScreen = withAuthRequired(
       const feeds = []
       for (const feed of pinned) {
         const model = new PostsFeedModel(store, 'custom', {feed: feed.uri})
-        model.setup()
         feeds.push(model)
       }
       pagerRef.current?.setPage(0)
@@ -169,6 +168,13 @@ const FeedPage = observer(
     })
     const isScreenFocused = useIsFocused()
 
+    React.useEffect(() => {
+      // called on first load
+      if (!feed.hasLoaded && isPageFocused) {
+        feed.setup()
+      }
+    }, [isPageFocused, feed])
+
     const doPoll = React.useCallback(
       (knownActive = false) => {
         if (