How to fast the data transfer rate with WebSocket module 'ws' in Espruino?

I have wrote some test codes:

function onInit(){
  var ssid = "ssid";
  var wifiOpts = {password:"pwd"};
  var wifi = require("Wifi");

  wifi.connect(ssid, wifiOpts, function(err){
    console.log("connected? err=", err, "info=", wifi.getIP());
    var WebSocket = require("ws");
    var host = "192.168.1.9";
    var ws = new WebSocket(host,{
      path: '/',
      port: 5004, // default is 80
      protocolVersion: 13, // websocket protocol version, default is 13
      origin: 'Espruino',
      keepAlive: 60,
    });

    ws.on('open', function() {
      console.log("connected");
      //ws.send('hello, server');
      var packet = "12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890";
      var pktNum = 0;
      var ta = 0;
      var id = setInterval(function(){
        var t1 = getTime();
        ws.send(btoa(packet));
        pktNum ++;
        console.log("Packet NO.: " + pktNum + ", time used: " + (t2 = getTime() - t1) + "s");
        ta += t2;
        if(pktNum >=101){
          console.log("total time used: " + ta +"s");
          clearInterval(id);
        }
      }, 100);
    });
  });
}

the result:

connected? err= null info= {
  "ip": "192.168.1.30",
  "netmask": "255.255.255.0",
  "gw": "192.168.1.1",
  "mac": "30:ae:a4:03:96:a8"
 }
connected
Packet NO.: 1, time used: 0.85709s
Packet NO.: 2, time used: 0.838764s
Packet NO.: 3, time used: 0.856456s
Packet NO.: 4, time used: 0.837004s
Packet NO.: 5, time used: 0.845455s
Packet NO.: 6, time used: 0.847384s
Packet NO.: 7, time used: 0.84427s
Packet NO.: 8, time used: 0.850653s
Packet NO.: 9, time used: 0.840083s
Packet NO.: 10, time used: 0.841126s
Packet NO.: 11, time used: 0.849597s
Packet NO.: 12, time used: 0.846575s
Packet NO.: 13, time used: 0.851111s
Packet NO.: 14, time used: 0.845253s
Packet NO.: 15, time used: 0.861927s
Packet NO.: 16, time used: 0.848568s
Packet NO.: 17, time used: 0.85375s
Packet NO.: 18, time used: 0.839241s
Packet NO.: 19, time used: 0.837366s
Packet NO.: 20, time used: 0.846501s
Packet NO.: 21, time used: 0.851264s
Packet NO.: 22, time used: 0.844203s
Packet NO.: 23, time used: 0.850979s
Packet NO.: 24, time used: 0.851601s
Packet NO.: 25, time used: 0.844725s
Packet NO.: 26, time used: 0.846098s
Packet NO.: 27, time used: 0.84291s
Packet NO.: 28, time used: 0.844193s
Packet NO.: 29, time used: 0.850243s
Packet NO.: 30, time used: 0.854025s
Packet NO.: 31, time used: 0.84941s
Packet NO.: 32, time used: 0.84723s
Packet NO.: 33, time used: 0.84363s
Packet NO.: 34, time used: 0.850008s
Packet NO.: 35, time used: 0.843929s
Packet NO.: 36, time used: 0.859503s
Packet NO.: 37, time used: 0.845025s
Packet NO.: 38, time used: 0.838622s
Packet NO.: 39, time used: 0.86317899999s
Packet NO.: 40, time used: 0.847434s
Packet NO.: 41, time used: 0.841337s
Packet NO.: 42, time used: 0.84749s
Packet NO.: 43, time used: 0.845084s
Packet NO.: 44, time used: 0.859161s
Packet NO.: 45, time used: 0.854041s
Packet NO.: 46, time used: 0.853847s
Packet NO.: 47, time used: 0.84596s
Packet NO.: 48, time used: 0.855874s
Packet NO.: 49, time used: 0.846709s
Packet NO.: 50, time used: 0.850626s
Packet NO.: 51, time used: 0.855101s
Packet NO.: 52, time used: 0.843922s
Packet NO.: 53, time used: 0.855193s
Packet NO.: 54, time used: 0.850098s
Packet NO.: 55, time used: 0.85086299999s
Packet NO.: 56, time used: 0.843604s
Packet NO.: 57, time used: 0.840063s
Packet NO.: 58, time used: 0.849205s
Packet NO.: 59, time used: 0.84311899999s
Packet NO.: 60, time used: 0.847484s
Packet NO.: 61, time used: 0.855748s
Packet NO.: 62, time used: 0.856332s
Packet NO.: 63, time used: 0.849081s
Packet NO.: 64, time used: 0.847368s
Packet NO.: 65, time used: 0.8664s
Packet NO.: 66, time used: 0.855494s
Packet NO.: 67, time used: 0.845644s
Packet NO.: 68, time used: 0.840538s
Packet NO.: 69, time used: 0.847404s
Packet NO.: 70, time used: 0.852032s
Packet NO.: 71, time used: 0.84936300000s
Packet NO.: 72, time used: 0.847706s
Packet NO.: 73, time used: 0.851532s
Packet NO.: 74, time used: 0.842296s
Packet NO.: 75, time used: 0.84484s
Packet NO.: 76, time used: 0.847341s
Packet NO.: 77, time used: 0.851096s
Packet NO.: 78, time used: 0.85451s
Packet NO.: 79, time used: 0.853806s
Packet NO.: 80, time used: 0.857314s
Packet NO.: 81, time used: 0.842491s
Packet NO.: 82, time used: 0.84421200000s
Packet NO.: 83, time used: 0.846194s
Packet NO.: 84, time used: 0.841761s
Packet NO.: 85, time used: 0.86257s
Packet NO.: 86, time used: 0.847736s
Packet NO.: 87, time used: 0.843611s
Packet NO.: 88, time used: 0.84158s
Packet NO.: 89, time used: 0.84169s
Packet NO.: 90, time used: 0.84392s
Packet NO.: 91, time used: 0.841432s
Packet NO.: 92, time used: 0.849577s
Packet NO.: 93, time used: 0.848673s
Packet NO.: 94, time used: 0.841546s
Packet NO.: 95, time used: 0.845739s
Packet NO.: 96, time used: 0.849719s
Packet NO.: 97, time used: 0.839512s
Packet NO.: 98, time used: 0.838894s
Packet NO.: 99, time used: 0.850167s
Packet NO.: 100, time used: 0.857364s
Packet NO.: 101, time used: 0.846186s
total time used: 85.66558500000s

per 230 bytes packet needs 850ms to be transfered to websocket server(nodejs).