Decrease Image downloading time with HttpURLConnection

This is piece of code is using to download images. Can somebody tell me how to optimize this code to decrease download time for each image?

URL url;
        HttpURLConnection connection = null;
        InputStream input = null;
        System.setProperty("http.keepAlive", "true");
        try {
            url = new URL(urlString);
            connection = (HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(HTTP_CONNECTION_TIMEOUT);
            connection.setRequestProperty("Connection", "Keep-Alive");
            input = connection.getInputStream();
            return BitmapFactory.decodeStream(input);
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return null;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            currentRequestInProgress.remove(urlString);
            if (connection != null)
                connection.disconnect();
            if(input != null){
                try {
                    input.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }

Buffered streams usually result in greatly improved performance:

input = new BufferedInputStream(connection.getInputStream());

The buffer size is 8kb per default, tuning it may be an option (but not without measuring).

And, if you download multiple images: parallelize it with multiple threads (most of the time is consumed by I/O waits anyway), this usually improves performance by factors.

StackExchange Code Review Q#46711, answer score: 6