Test some performance stuff

src/create-element.js

@@ -84,6 +84,10 @@ export function createVNode(type, props, key, ref, original) {
 	return vnode;
 }
 
+// @ts-ignore
+export const EMPTY_VNODE = createVNode(null, {});
+EMPTY_VNODE._children = [];
+
 export function createRef() {
 	return { current: null };
 }

src/diff/children.js

@@ -1,6 +1,6 @@
 import { diff, unmount, applyRef } from './index';
-import { createVNode, Fragment } from '../create-element';
-import { EMPTY_OBJ, EMPTY_ARR, INSERT_VNODE, MATCHED } from '../constants';
+import { createVNode, Fragment, EMPTY_VNODE } from '../create-element';
+import { EMPTY_ARR, INSERT_VNODE, MATCHED } from '../constants';
 import { isArray } from '../util';
 import { getDomSibling } from '../component';
 
@@ -67,9 +67,9 @@ export function diffChildren(
 		// At this point, constructNewChildrenArray has assigned _index to be the
 		// matchingIndex for this VNode's oldVNode (or -1 if there is no oldVNode).
 		if (childVNode._index === -1) {
-			oldVNode = EMPTY_OBJ;
+			oldVNode = EMPTY_VNODE;
 		} else {
-			oldVNode = oldChildren[childVNode._index] || EMPTY_OBJ;
+			oldVNode = oldChildren[childVNode._index] || EMPTY_VNODE;
 		}
 
 		// Update childVNode._index to its final index

src/diff/index.js

@@ -1,4 +1,5 @@
 import {
+	EMPTY_ARR,
 	EMPTY_OBJ,
 	MODE_HYDRATE,
 	MODE_SUSPENDED,
@@ -498,7 +499,7 @@ function diffElementNodes(
 				dom.innerHTML = newHtml.__html;
 			}
 
-			newVNode._children = [];
+			newVNode._children = EMPTY_ARR;
 		} else {
 			if (oldHtml) dom.innerHTML = '';
 

src/diff/props.js

@@ -135,7 +135,10 @@ export function setProperty(dom, name, value, oldValue, namespace) {
 
 		if (typeof value == 'function') {
 			// never serialize functions as attribute values
-		} else if (value != null && (value !== false || name[4] === '-')) {
+		} else if (
+			value != null &&
+			(value !== false || (name.length > 4 && name[4] === '-'))
+		) {
 			dom.setAttribute(name, name == 'popover' && value == true ? '' : value);
 		} else {
 			dom.removeAttribute(name);

src/render.js

@@ -1,6 +1,6 @@
 import { EMPTY_OBJ } from './constants';
 import { commitRoot, diff } from './diff/index';
-import { createElement, Fragment } from './create-element';
+import { createElement, Fragment, EMPTY_VNODE } from './create-element';
 import options from './options';
 import { slice } from './util';
 
@@ -39,7 +39,7 @@ export function render(vnode, parentDom, replaceNode) {
 		// Determine the new vnode tree and store it on the DOM element on
 		// our custom `_children` property.
 		vnode,
-		oldVNode || EMPTY_OBJ,
+		oldVNode || EMPTY_VNODE,
 		EMPTY_OBJ,
 		parentDom.namespaceURI,
 		!isHydrating && replaceNode