Android : ViewPager scroll lagging in Android

I am using a ViewPager to show various GridViews with a set of images for each one.

I just copy and pasted all the images to the drawables folder and they had 300px X 300px each, when swiping between the different grids the swipe lagged a lot, I tried resizing the images to half the size, it got better but the problem persists.

Then I tried to load each image using an AsyncTask like this:

public class ImageAdapter extends BaseAdapter {
private Context mContext;
private Integer[] mSeries;

public ImageAdapter(Context c, int n) {
    super();
    this.mContext = c;
    this.mSeries = ArrayImages.getImages(n);
}

public int getCount() {
    return mSeries.length;
}

public Object getItem(int position) {
    return null;
}

public long getItemId(int position) {
    return 0;
}

// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {
        // if it's not recycled, initialize some attributes
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(200, 200));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setPadding(8, 8, 8, 8);
    } else {
        imageView = (ImageView) convertView;
    }

    imageView.setDrawingCacheEnabled(true);
    new LoadImage(imageView, position).execute();
    return imageView;
}

class LoadImage extends AsyncTask<Object, Void, Integer> {

    private ImageView imv;
    private int position;

    public LoadImage(ImageView imv, int pos) {
        this.imv = imv;
        this.position = pos;
    }

    @Override
    protected Integer doInBackground(Object... params) {
        return mSeries[position];
    }
    @Override
    protected void onPostExecute(Integer result) {
        if(result != 0 && imv != null){
            imv.setVisibility(View.VISIBLE);
            imv.setImageResource(result);
        }else{
            imv.setVisibility(View.GONE);
        }
    }
}

But the problem still persists and since there are a 250 images I made some arrays to keep them all and when I need them I just ask: ArrayImages.getImages(n) not sure if this might be the problem.

Since my FragmentPagerAdapter has to create all the 16 GridFragment and get those arrays:

public class ViewPagerAdapter extends FragmentStatePagerAdapter {

private int NumbOfTabs = 16; // Store the number of tabs, this will also be passed when the ViewPagerAdapter is created


// Build a Constructor and assign the passed Values to appropriate values in the class
public ViewPagerAdapter(FragmentManager fm) {
    super(fm);
}

//This method return the fragment for the every position in the View Pager
@Override
public Fragment getItem(int index) {
    // TODO Auto-generated method stub
    switch (index) {
        case 0:
            return new GridFragment(1);

        case 1:
            return new GridFragment(2);
        ...
        case 16:
            return new GridFragment(16);

What can I do to improve the loading and remove the lag?