diff --git a/core/block_dragger.js b/core/block_dragger.js
index 0fed99b36..47624a335 100644
--- a/core/block_dragger.js
+++ b/core/block_dragger.js
@@ -162,9 +162,9 @@ Blockly.BlockDragger.prototype.startBlockDrag = function(currentDragDeltaXY,
     this.draggingBlock_.bringToFront();
   }
 
-  // // During a drag there may be a lot of rerenders, but not field changes.
-  // // Turn the cache on so we don't do spurious remeasures during the drag.
-  // Blockly.Field.startCache();
+  // During a drag there may be a lot of rerenders, but not field changes.
+  // Turn the cache on so we don't do spurious remeasures during the drag.
+  Blockly.Field.startCache();
   this.workspace_.setResizesEnabled(false);
   Blockly.BlockAnimations.disconnectUiStop();
 
diff --git a/core/block_render_svg.js b/core/block_render_svg.js
index c12903211..a1d4af37e 100644
--- a/core/block_render_svg.js
+++ b/core/block_render_svg.js
@@ -391,8 +391,6 @@ Blockly.BlockSvg.prototype.renderFields_ = function(fieldList,
       root.setAttribute('display', 'none');
     }
   }
-
-
   return this.RTL ? -cursorX : cursorX;
 };
 
diff --git a/core/connection.js b/core/connection.js
index bff427814..1f97d81fe 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -431,6 +431,16 @@ Blockly.Connection.prototype.isConnectionAllowed = function(candidate) {
       break;
     }
     case Blockly.NEXT_STATEMENT: {
+      // Don't let a block with no next connection bump other blocks out of the
+      // stack.  But covering up a shadow block or stack of shadow blocks is
+      // fine.  Similarly, replacing a terminal statement with another terminal
+      // statement is allowed.
+      if (candidate.isConnected() &&
+          !this.sourceBlock_.nextConnection &&
+          !candidate.targetBlock().isShadow() &&
+          candidate.targetBlock().nextConnection) {
+        return false;
+      }
       break;
     }
     default: