One issue I have with this is that due to the commonality of spinners, I associate the wait cursor with waiting on the browser (memory issue, temporary CPU spike, large js script running) rather than an waiting on the results of an ajax request.
For me at least, using this technique would probably cause me to perceive the site as being slower or more resource intensive than it truly is.
For me at least, using this technique would probably cause me to perceive the site as being slower or more resource intensive than it truly is.