Is measuring js execution time a way to tell how quickly the app is responding to requests?

I have something like a microtime() function at the very start of my node.js / express app.

function microtime (get_as_float) {
    // Returns either a string or a float containing the current time in seconds and microseconds  
    // 
    // version: 1109.2015
    // discuss at: http://phpjs.org/functions/microtime
    // +   original by: Paulo Freitas
    // *     example 1: timeStamp = microtime(true);
    // *     results 1: timeStamp > 1000000000 && timeStamp < 2000000000
    var now = new Date().getTime() / 1000;
    var s = parseInt(now, 10);

    return (get_as_float) ? now : (Math.round((now - s) * 1000) / 1000) + ' ' + s;
}

The code of the actual app looks something like this:

application.post('/', function(request, response) {
  t1 = microtime(true);
  //code
   //code
   response.send(something);
   console.log("Time elapsed: " + (microtime(true) - t1));
}

Time elapsed: 0.00599980354309082

My question is, does this mean that from the time a POST request hits the server to the time a response is sent out is give or take ~0.005s?

I've measured it client-side but my internet is pretty slow so I think there's some lag that has nothing to do with the application itself. What's a quick and easy way to check how quickly the requests are being processed?