The new renderer is causing Flash objects to be instantiated before any nested param nodes have been added, they are read and parsed at creation and never touched again. EDIT: I'm assuming the Flash object is loaded immediately upon insertion into the DOM and not at the next tick.

This only happens on IE AFAIK (all versions including Edge). Related to the performance-special-case in the renderer?

cc @spicyj 

/**
 * Copyright 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule DOMLazyTree
 */
'use strict';
var createMicrosoftUnsafeLocalFunction = require('createMicrosoftUnsafeLocalFunction');
var setTextContent = require('setTextContent');
/**
 * In IE (8-11) and Edge, appending nodes with no children is dramatically
 * faster than appending a full subtree, so we essentially queue up the
 * .appendChild calls here and apply them so each node is added to its parent
 * before any children are added.
 *
 * In other browsers, doing so is slower or neutral compared to the other order
 * (in Firefox, twice as slow) so we only do this inversion in IE.
 *