read an high precision adc like hx711

That's a shame - I'd have thought that especially the code posted above, when compiled, would be more than fast enough.

The other option is something like:

var s = new SPI();
s.setup({ miso : data_in_pin, sck : clk_out_pin });
var d = s.send([0b10101010,0b10101010,0b10101010­,0b10101010,0b10101010,0b10101010,0b1000­0000]);
var v = 0;
for (var i=0;i<5;i++) {
  v = (v<<1) | ((d[i]>>6)&1);
  v = (v<<1) | ((d[i]>>4)&1);
  v = (v<<1) | ((d[i]>>2)&1);
  v = (v<<1) | (d[i]&1);
}