Slow performance downloading files using SFTP in Android

[casolorz]

I am using JSch to perform an SFTP download in Android. This is on a LAN with 802.11n and an SFTP server on a wired gigabit connection. I am getting about 8 mbytes/sec on a laptop (also 802.11n) with the same code but I am only getting 40kbytes/sec on Android. Are there some flags or something I need to turn on to get this to transfer faster? I have tried it on a Nexus 5 and a Nexus 6, both with Android 5.1. I also tried a couple of apps and one downloaded the file at 230kbytes/sec and the other right around 40kbytes/sec so I'm guessing one of them has the same issue I do.

My test code is this:

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Thread thread = new Thread() {
            @Override
            public void run() {
                try {
                    JSch jsch = new JSch();

                    jsch.setConfig("StrictHostKeyChecking", "no");
                    Session session = jsch.getSession("ftptest", "192.168.1.205");

                    session.setPort(22);
                    session.setPassword("password");
                    session.connect();
                    ChannelSftp channel = (ChannelSftp) session.openChannel("sftp");
                    channel.connect();
                    SftpProgressMonitor monitor = new SftpProgressMonitor() {
                        long finalCount = 0;
                        long start = -1;

                        @Override
                        public void init(int op, String src, String dest, long max) {
                            start = System.currentTimeMillis();
                        }

                        @Override
                        public boolean count(long count) {
                            finalCount += count;
                          /*  long took = (System.currentTimeMillis() - start) / 1000;
                            if (took > 0) {
                                Log.w("SFTP", "Transferred so far " + finalCount + " at speed bytes/sec " + (finalCount / took));
                            }*/
                            return true;
                        }

                        @Override
                        public void end() {
                            long took = (System.currentTimeMillis() - start) / 1000;
                            Log.w("SFTP", "Transferred " + finalCount + " in " + took + " speed bytes/sec " + (finalCount  / took ));
                        }
                    };
                    InputStream stream = channel.get("file", monitor);
                    int read = -1;
                    byte[] bs = new byte[8192];
                    while((read = stream.read(bs)) >= 0){
                        //do nothing
                    }
                } catch (JSchException e) {
                    e.printStackTrace();
                } catch (SftpException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        };
        thread.start();
    }


}

[casolorz]

I would like to add that it is a lot faster, about 160kbytes/sec if I use the get method that writes into a file directly instead of giving me an input stream. It is still a lot slower than running it outside Android though.