Does Ajax detoriate performance?

Question

Does excess use of AJAX affects performance? In context of big size web-applications, how do you handle AJAX requests to control asynchronous requests?

Answer 1

excess use of anything degrades performance; using AJAX where necessary will improve performance, especially if the alternative is a complete full-page round-trip to the server [a 'postback' in asp.net terminology]

Answer 2

There are two sides to this story.

AJAX generally improves the performance from the client's perspective. Rather than loading an entire page, a smaller amount of data is requested from the server when it is needed. Given that a HTML page often references many dependent files (images, css, javascript,etc, each requiring a hit from the server (or the cache)) the client performance from judicious use of AJAX can be remarkable.

On the server-side, the issue becomes one of having many more connections to manage. Polling applications, such as in-browser chat in particular, can really start to increase the load on the server because the browser is now hitting the server much more rapidly. In a typical dynamic application (where the response is generated by code rather than from a static file) you may start running into issues - but these are generally balanced by the fact that the complexity of your request is often much lower (again, you aren't generating the entire page but a small subset of the page) and so therefore your platform can probably get a higher throughput in any case.

The exact outcome of any performance issue is going to depend on a number of factors including your server, platform, framework, and prevailing climactic conditions at the time.

My ultimate advice - focus on creating a good user experience, develop intelligently, collect as many metrics as you can and optimise when you know you need it.