Use GET instead of POST for AJAX call
It is easy to use GET instead of POST, but Drupal sends a lot of information about dom-elements and loaded css/js, so that it is often too long for a GET request..

var ax = new Drupal.ajax("element-name", this, element_settings);
ax.options.type = "GET";


If you do not use these, you can strip them:

//Override parameters for Get Requests
var backup = Drupal.ajax.prototype.beforeSerialize;
Drupal.ajax.prototype.beforeSerialize = function(element, options) {
  if(options.type != "GET") backup.call(this, element, options);
}