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

Is there some method to enchance the performance of 'ws' ?

Chances are it's this code that is slowing things down:

https://github.com/espruino/EspruinoDocs/blob/master/modules/ws.js#L230

You could probably do something like this to make Espruino head through it 32 bits at a time instead of 8:

masked = new Uint32Array(1+((msg.length+3)>>2));
var m8 = new Uint8Array(masked.buffer,0,4+msg.length);
m8.set(mask,0);
m8.set(msg,4);
var m = masked[0];
for (var i=masked.length-1;i>0;i--)masked[i]^=m;
// E.mapInPlace could be even faster here
this.socket.write(m8);

But you'd have to have a play around yourself - I haven't tested that.