Listview lags behind even when saving images with Picasso

I have a list view that contains images and when I scroll past a certain point the delays are scrolling.

I use the Picasso

following code as well to make sure the images are loaded into memory on a background thread.

    picasso
        .load(f)
        .fit()
        .error(R.drawable.broken_image)
        .into(viewHolder.imageView, loadDoneCallback);

      

        
        
        
      

    

If all my entries ListView

are loading the same image, there is no lag, so the problem is with loading the image from memory into viewHolder.imageView

.

Another data point is that I see lagging on my device O + O with Android 4.4.4

. However, my Nexus 5 running under Android 5.1

doesn't seem to have this issue. Both seem to be using a heap size of around 128MB +. At ~ 40KB per thumb and 3 thumbs per line and a total of 50 lines (I see a lag as I go past the first 10 lines), my total in-memory image size should be ~ 6 MB and all images should be included into the cache (even though the download is done on a background thread anyway).

When I repeated the problem several times by scrolling up and down, I was able to get the message Skipped x frames

.

06-03 22:24:30.279    2382-2382/xxx I/Choreographer﹕ Skipped 58 frames!  The application may be doing too much work on its main thread.

      

        
        
        
      

    

Again, I am assuming that this work, which is happening on the main thread, has to do with the individual images being loaded Picasso

from their cache into ImageView

. I'm guessing it can't be related to other layout related calculations etc., since using the same image for all posts ListView

works great.

Is this expected or am I making a rookie mistake?

UPDATE: this is my code getView

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    View view;
    ViewHolder viewHolder = new ViewHolder();
    final String imageId = getItem(position);
    if (convertView == null) {
        view = inflator.inflate(R.layout.image_row_home, parent, false);
        viewHolder.imageView = (ImageView) view.findViewById(R.id.img);
        viewHolder.imageView.getLayoutParams().height = imageWidth;
        viewHolder.imageView.getLayoutParams().width = imageWidth;
        viewHolder.imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        viewHolder.imageId = imageId;
        view.setTag(viewHolder);
    } else {
        view = convertView;
        viewHolder = ((ViewHolder) view.getTag());
        // If this view is already for the image we want, no need to recreate it.
        if (viewHolder.imageId.equals(imageId)) {
            return view;
        }
        viewHolder.imageId = imageId;
    }

    final File f = getImageFileForPosition(position);
    picasso
        .load(f)
        .fit()
        .error(R.drawable.broken_image)
        .into(viewHolder.imageView);
}