We here at Port80 get a great amount of feedback from people who like to tune Web site and app performance, and we have come across a great fallacy that deserves a special mention. No disrespect to Mr. Bill Maher, but we got our own new rule.
New Rule: High bandwidth/broadband users don't necessarily have fast and powerful computers.
Now, this might seem obvious, but clearly it is not believed by the great mass of technologists out there.
For example, more and more sites use Flash or very intensive multimedia. Now, with your average, more evolved Web designers, there is often at least some choice offered to the Web user between some high-end experience and a low-end experience (Click here for broadband, click there for crappy ol' dial-up). Smarter site designers sniff all this out with JavaScript and perform some basic calculations on available bandwidth -- so the user doesn't have to make a choice.
Unfortunately, this isn't really good enough.
For example, we notice that many Flash-built sites don't perform that well at all. The problem is that you may download some Flash-style video or animation rapidly, but then the Web user has to play it back on the local system. If that system is not the latest box, is running lots of applications, has little memory, or anything else less than ideal, the playback may skip, stall, or sputter along. Add in a little network jitter if it is being streamed, and you have a really unpleasant experience. Of course, fingers point right away, and target the network or the Web server, but remember folks: clients affect things too!
So, if you are going to get crazy with client-side playback, be it Flash, Ajax or the like, don't forget all of your many different users’ vastly different system conditions. You can figure it out, believe it or not, but we leave that to you, as they say in Computer Science books, "as an exercise."
Best,
Port80
P.S. IIS performance rules.