Ajax Performance

Real world case study in slimming down bandwidth consumption

One issue I keep coming back to here is the hidden, cumulative cost of bandwidth as traffic scales. Another case study showed up a few days ago from Jeff Atwood at Coding Horror. Using traffic patterns from a popular article published in February, he found 4 useful techniques for bandwidth optimization: offload images to a third party, use HTTP compression, offload RSS hosting, and compress JavaScript and CSS.

Offloading images ties in well to my discussion of connection parallelism back in December. Loyal readers will recall the tip for using DNS wildcards to trick the browser into assigning more connections to your host, but that does nothing to reduce your bandwidth costs. The solution I suggested is appropriate when you want to maximize connection parallelism and have bandwidth to spare.

Images hosted by a third party are allocated two connections, and none of the bandwidth tracks back to your infrastructure. I’m curious whether any of the third party hosts allow you to make use of the DNS hack to also get the benefits of 6 connections over their pipes. That would truly be the best of both worlds — outsourced hosting and as much parallelism as the browser can handle.

Jeff recommends using Amazon S3 for image hosting, and that echoes what I’ve heard from numerous other users. At $0.20 per GB transferred, it’s hard to argue with the economics. This is a great solution if you have the time or energy. If anyone knows whether DNS wildcarding works with S3, I would love to hear about it.