its happening

src/state/auto-scroller/get-best-scrollable-droppable.js

@@ -3,6 +3,7 @@ import memoizeOne from 'memoize-one';
 import invariant from 'tiny-invariant';
 import { type Position } from 'css-box-model';
 import isPositionInFrame from '../visibility/is-position-in-frame';
+import { toDroppableList } from '../dimension-structures';
 import type {
   DroppableId,
   DroppableDimension,
@@ -12,8 +13,7 @@ import type {
 
 const getScrollableDroppables = memoizeOne(
   (droppables: DroppableDimensionMap): DroppableDimension[] => (
-    Object.keys(droppables)
-      .map((id: DroppableId): DroppableDimension => droppables[id])
+    toDroppableList(droppables)
       .filter((droppable: DroppableDimension): boolean => {
         // exclude disabled droppables
         if (!droppable.isEnabled) {

src/state/dimension-structures.js

@@ -1,4 +1,5 @@
 // @flow
+import memoizeOne from 'memoize-one';
 import type {
   DroppableId,
   DraggableId,
@@ -8,24 +9,28 @@ import type {
   DraggableDimensionMap,
 } from '../types';
 
-export const toDroppableMap =
+export const toDroppableMap = memoizeOne(
   (droppables: DroppableDimension[]): DroppableDimensionMap =>
     droppables.reduce((previous, current) => {
       previous[current.descriptor.id] = current;
       return previous;
-    }, {});
+    }, {})
+);
 
-export const toDraggableMap =
+export const toDraggableMap = memoizeOne(
   (draggables: DraggableDimension[]): DraggableDimensionMap =>
     draggables.reduce((previous, current) => {
       previous[current.descriptor.id] = current;
       return previous;
-    }, {});
+    }, {})
+);
 
-export const toDroppableList =
+export const toDroppableList = memoizeOne(
   (droppables: DroppableDimensionMap): DroppableDimension[] =>
-    Object.keys(droppables).map((id: DroppableId): DroppableDimension => droppables[id]);
+    Object.keys(droppables).map((id: DroppableId): DroppableDimension => droppables[id])
+);
 
-export const toDraggableList =
+export const toDraggableList = memoizeOne(
   (draggables: DraggableDimensionMap): DraggableDimension[] =>
-    Object.keys(draggables).map((id: DraggableId): DraggableDimension => draggables[id]);
+    Object.keys(draggables).map((id: DraggableId): DraggableDimension => draggables[id])
+);

src/state/get-draggables-inside-droppable.js

@@ -1,7 +1,7 @@
 // @flow
 import memoizeOne from 'memoize-one';
+import { toDraggableList } from './dimension-structures';
 import type {
-  DraggableId,
   DraggableDimension,
   DroppableDimension,
   DraggableDimensionMap,
@@ -11,8 +11,7 @@ export default memoizeOne(
   (droppable: DroppableDimension,
     draggables: DraggableDimensionMap,
   ): DraggableDimension[] =>
-    Object.keys(draggables)
-      .map((id: DraggableId): DraggableDimension => draggables[id])
+    toDraggableList(draggables)
       .filter((draggable: DraggableDimension): boolean => (
         droppable.descriptor.id === draggable.descriptor.droppableId
       ))

src/state/get-droppable-over.js

@@ -6,6 +6,7 @@ import isPositionInFrame from './visibility/is-position-in-frame';
 import { patch } from './position';
 import { expandByPosition } from './spacing';
 import { clip } from './droppable-dimension';
+import { toDroppableList } from './dimension-structures';
 import type {
   Scrollable,
   DraggableDimension,
@@ -132,28 +133,27 @@ export default ({
   previousDroppableOverId,
 }: Args): ?DroppableId => {
   const maybe: ?DroppableDimension =
-    Object.keys(droppables)
-      .map((id: DroppableId): DroppableDimension => droppables[id])
+      toDroppableList(droppables)
       // only want enabled droppables
-      .filter((droppable: DroppableDimension) => droppable.isEnabled)
-      .find((droppable: DroppableDimension): boolean => {
-        // If previously dragging over a droppable we give it a
-        // bit of room on the subsequent drags so that user and move
-        // items in the space that the placeholder takes up
-        const withPlaceholder: ?Rect = getClippedRectWithPlaceholder({
-          draggable, draggables, droppable, previousDroppableOverId,
+        .filter((droppable: DroppableDimension) => droppable.isEnabled)
+        .find((droppable: DroppableDimension): boolean => {
+          // If previously dragging over a droppable we give it a
+          // bit of room on the subsequent drags so that user and move
+          // items in the space that the placeholder takes up
+          const withPlaceholder: ?Rect = getClippedRectWithPlaceholder({
+            draggable, draggables, droppable, previousDroppableOverId,
+          });
+
+          if (!withPlaceholder) {
+            return false;
+          }
+
+          // Not checking to see if visible in viewport
+          // as the target might be off screen if dragging a large draggable
+          // Not adjusting target for droppable scroll as we are just checking
+          // if it is over the droppable - not its internal impact
+          return isPositionInFrame(withPlaceholder)(target);
         });
 
-        if (!withPlaceholder) {
-          return false;
-        }
-
-        // Not checking to see if visible in viewport
-        // as the target might be off screen if dragging a large draggable
-        // Not adjusting target for droppable scroll as we are just checking
-        // if it is over the droppable - not its internal impact
-        return isPositionInFrame(withPlaceholder)(target);
-      });
-
   return maybe ? maybe.descriptor.id : null;
 };

src/state/move-cross-axis/get-best-cross-axis-droppable.js

@@ -5,6 +5,7 @@ import { closest } from '../position';
 import isWithin from '../is-within';
 import { getCorners } from '../spacing';
 import isPartiallyVisibleThroughFrame from '../visibility/is-partially-visible-through-frame';
+import { toDroppableList } from '../dimension-structures';
 import type {
   Axis,
   DroppableDimension,
@@ -50,8 +51,7 @@ export default ({
     sourceClipped[axis.start],
     sourceClipped[axis.end]
   );
-  const candidates: DroppableDimension[] = Object.keys(droppables)
-    .map((id: DroppableId): DroppableDimension => droppables[id])
+  const candidates: DroppableDimension[] = toDroppableList(droppables)
     // Remove the source droppable from the list
     .filter((droppable: DroppableDimension): boolean => droppable !== source)
     // Remove any options that are not enabled

src/state/publish/get-drag-positions.js

@@ -40,13 +40,9 @@ export default ({
   const centerDiff: Position = subtract(newClientBorderBoxCenter, oldClientBorderBoxCenter);
   // const displacement: Position = negate(centerDiff);
 
-  console.log('center offset', centerDiff);
-
   const clientSelection: Position = add(
     oldInitial.client.selection, centerDiff
   );
-  console.log('old client selection', oldInitial.client.selection);
-  console.log('new client selection', clientSelection);
 
   const initial: DragPositions = (() => {
     const client: ItemPositions = {