use css animation for perf

site/common/styles/common.less

@@ -262,6 +262,18 @@ a {
   }
 }
 
+@keyframes upDownMove {
+  0% {
+    transform: translateY(0);
+  }
+  50% {
+    transform: translateY(-6px);
+  }
+  100% {
+    transform: translateY(0);
+  }
+}
+
 @keyframes pageEnter {
   from {
     opacity: 0;

site/component/Home/Banner.jsx

@@ -1,7 +1,6 @@
 import React from 'react';
 import { Link } from 'react-router';
 import ScrollElement from 'rc-scroll-anim/lib/ScrollElement';
-import TweenOne from 'rc-tween-one';
 import GitHubButton from 'react-github-button';
 import 'react-github-button/assets/style.css';
 import { Icon } from 'antd';
@@ -33,9 +32,7 @@ export default class Banner extends React.Component {
             <GitHubButton key="github-button" type="stargazers"
               namespace="ant-design" repo="ant-design" />
           </QueueAnim>
-          <TweenOne className="down" animation={{ y: 10, duration: 800, yoyo: true, repeat: -1 }}>
+          <Icon type="down" className="down" />
-            <Icon type="down" />
-          </TweenOne>
         </ScrollElement>
       </section>
     );

site/component/Home/index.jsx

@@ -85,6 +85,9 @@ export default class Home extends React.Component {
       #footer a {
         color: #eee;
       }
+      .down {
+        animation: upDownMove 1.2s ease-in-out infinite;
+      }
     `;
   }