Android程序开始启动时出现白屏（大约1秒）

<activity android:name=".activity.WelcomeActivity"
android:theme="@style/Theme.BackgroundTranslucent"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>

<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>

<!--启动时白色-->
<style name="Theme.BackgroundTranslucent" parent="@android:style/Theme.Translucent">
<item name="android:windowBackground">@null</item>
<item name="android:windowNoTitle">true</item>
</style>