Posting to admin-ajax from front end. Is this redirect ok?

Question

I'm posting a form to admin-ajax and the redirect use to be within the success handler. That was taking too long to receive from the server then redirect, even though it was only a small json response giving a success message. I've since moved the redirect to execute after the .ajax() call. Is there any chance the redirect could execute before the AJAX posted? I know AJAX is asynchronous so it's executing in the background.

    jQuery.ajax({
      type:"POST",
      url:admin_ajaxurl,
      dataType: "Json",
      data: {
        action: "lp_contact",
        post: postData
      },
      beforeSend: function(jqXHR, data, setting){

      },
      success: function(data){          

      },
      error: function(data) {
      }

    }); // End update prospect
    window.location.replace("http://www.example.com/thank-you-landing-page/");
    return false;

Answer 1

The problem could be in using admin ajax. If you switch to a different endpoint, the process may speed up.

I've used ajax flow on a few sites and you should see a performance gain: https://wordpress.org/support/view/plugin-reviews/ajaxflow

Check out some best practices here:
https://10up.github.io/Engineering-Best-Practices/php/#libraries