Help optimizing this - converting 1024 byte arraybuffer to string after reversing bits in each byte

Just added E.reverseByte - you can get it in the latest build, or can wait for 1v63:

  var preamble = E.toArrayBuffer("DIM\x00\x00\x80\x40");
  LCD.flip = function () {
    var d = new Uint8Array(this.buffer.length+preamble.length);
    d.set(preamble,0);
    d.set(new Uint8Array(this.buffer).map(E.reverseByte), preamble.length);
    this.i2c.writeTo(0x27,d); 
  };