Fix drag hover performance (frontend-collective#503)

* codesandbox relies on version 1.2.XX

* only do dragHover work after raf

Author: wombleton

package.json

@@ -95,7 +95,7 @@
     "babel-eslint": "^10.0.1",
     "babel-jest": "^23.6.0",
     "babel-loader": "^8.0.4",
-    "codesandbox": "^1.2.10",
+    "codesandbox": "~1.2.10",
     "coveralls": "^3.0.1",
     "cross-env": "^5.1.6",
     "enzyme": "^3.10.0",

src/utils/dnd-manager.js

@@ -232,11 +232,15 @@ export default class DndManager {
           return;
         }
 
-        this.dragHover({
-          node: draggedNode,
-          path: monitor.getItem().path,
-          minimumTreeIndex: dropTargetProps.listIndex,
-          depth: targetDepth,
+        // throttle `dragHover` work to available animation frames
+        cancelAnimationFrame(this.rafId);
+        this.rafId = requestAnimationFrame(() => {
+          this.dragHover({
+            node: draggedNode,
+            path: monitor.getItem().path,
+            minimumTreeIndex: dropTargetProps.listIndex,
+            depth: targetDepth,
+          });
         });
       },