The most simple method would be to add var ajaxTime= new Date().getTime();
before the Ajax call and in the done
get the current time to calculate how long the Ajax call took to make.
var ajaxTime= new Date().getTime();
$.ajax({
type: "POST",
url: "some.php",
}).done(function () {
var totalTime = new Date().getTime()-ajaxTime;
// Here I want to get the how long it took to load some.php and use it further
});
Or in case of you want to know how long time this take on the server side.
Do the same and print the time in the return value from some.php.