Frame drop when changed playback speed

Frame drop occurs when the playback speed is changed.
For example, playing "Youtube DASH" > "Google Glass H264(MP4)" causes a frame drop.

Is there anything I can do to improve it?

### Confirmation environment
package : com.google.android.exoplayer2.demo
branch : ```release-v2```、```dev-v2```

### Changes
com.google.android.exoplayer2.demo.PlayerActivity
```
player =
new SimpleExoPlayer.Builder(/* context= */ this, renderersFactory)
.setTrackSelector(trackSelector)
.build();
player.addListener(new PlayerEventListener());
player.setAudioAttributes(AudioAttributes.DEFAULT, /* handleAudioFocus= */ true);
player.setPlayWhenReady(startAutoPlay);
player.addAnalyticsListener(new EventLogger(trackSelector));
player.setPlaybackParameters(new PlaybackParameters(1.5F)); ← Added
```