Why android animation in my app is not as smooth as goLauncher animations?

Why android animation in my app is not as smooth as goLauncher animations?

I am using animation for item click of GridView. My animation file is
expand_then_contract.xml as below
<set xmlns:android="http://schemas.android.com/apk/res/android" >
<scale
android:duration="500"
android:fromXScale="1"
android:fromYScale="1"
android:pivotX="50%"
android:pivotY="50%"
android:toXScale="1.1"
android:toYScale="1.1" />
<scale
android:duration="500"
android:fromXScale="1.1"
android:fromYScale="1.1"
android:pivotX="50%"
android:pivotY="50%"
android:startOffset="500"
android:toXScale="1"
android:toYScale="1" />
</set>
And I'm applying it in the onItemClickListener of GridView as below
onItemClick(... View view ..)
{
Animation expand_contract = AnimationUtils.loadAnimation(this,
R.anim.expand_then_contract);
view.bringToFront();
view.clearAnimation();
view.setAnimation(expand_contract);
view.startAnimation(expand_contract);
}
It is working as expected. But it gets stuck in between. At some point
when it is contracting back to normal position, for a moment it freezes.
Why does this happen. Why can't animation in my code work as smoothly as
they make it in GoLauncher Animations. Do they use any external libraries.