Does Ajax detoriate performance?

Question

I was just wondering if excess use of Ajax affects performance? In context of big size web-applications how to handle ajax request to control asynchronous requests

Answer 1

AJAX itself (being asynchronous requests).. No not generally.

However if you have an abundance of javascript and markup and have large amounts of data transferred via your xmlhttprequests then yes you can see a performance hit. It really depends on how you want your website to function any degredation is generally avoidable if sculpted correctly.

Answer 2

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 3

Ajax is just an ordinary HTTP request, so as long as your server can handle those requests it won't be a problem. The upside to Ajax is faster perceived performance by the user, since the page doesn't have to reload and redraw itself for every user action.

If scalability is a concern, I'm sure you are also looking at scaling the system horizontally by adding more web servers to the farm. Same goes with even non-Ajax web apps anyway.

Answer 4

If the site is busy then it will, eventually, kill the server, unless your in a farm. As to the site itself it shouldn't.

Answer 5

What kind of "excessive use" are we talking?

Answer 6

AJAX, like any technology can be a good thing or a bad thing depending on the situation and how it is implemented. If you have a specific need for the asynchronous process then it is a good tool to use. However, if you use it irresponsibly you can get into trouble. If you do use it, try to find a good framework that does most of the heavy lifting and be aware of some of the downsides of AJAX... http://learningremix.net/w2007integ/vangoori/2007/01/the_downsides_of_ajax.shtml

Answer 7

Performance of what exactly? I'm going to assume you meant performance of an application in terms of user experience.

What Ajax appears to be best at is causing network traffic only when it's needed. Rather than downloading a honkin' great web page in one hit, it downloads only what's needed in as quick a manner as possible.

Then, if you do something that needs more info, it goes and gets it from the network then.

This means unused stuff is never downloaded (if you design it right, of course - bad code can be written in Ajax as much as any other environment).

I prefer to mix Ajax methods for data transfer and a client-side library like jQuery for pretty interface.

Answer 8

Depending on the situation, AJAX may have a performance overhead or it can actually have better performance than an equivelantly functioning web site that doesn't use AJAX.

It's very easy to overuse AJAX to overload the server with tons of frivilous requests and it can also be a burden on the client's CPU. Conversely, AJAX can also be used to deliver small bits of HTML and other code rather than a whole page for each request, which is at least less of a burden on the server.

Answer 9

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.

Answer 10

I would agree with quite a few other posts in here. If you are using it in an intelligent way (ie, not using ajax every 30 seconds), then it will be fine. I use ajax on my website (and there is also a js free version) and from a clients perspective, the ajax version loads at anywhere from near-equal speeds to four times faster. It all depends on the design (graphics and other content) of the website and what you are updating.

The downside is, since you have to load some frameworks (even if you create your own like I have) you will have a bit slower of a load for the first page, or any full refreshes, and it does increase the processing load a bit. But that is just because the ajax has increased productivity and therefore the user can make more requests/updates