hrtime.js

// high-resolution time diff in milliseconds
function hrmstime(t) {
    if (t) {
        t = process.hrtime(t);
        return (t[0] * 1e9 + t[1]) / 1e6;
    }
    return process.hrtime();
}


// Start time
var time = hrmstime();

// Run the code
slowFn();

// Time diff
time = hrmstime(time);

console.log('Done in %d ms', hrmstime(time));
// -> Done in 22.555161 ms