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Understanding Web Performance and Bandwidth
by Brian D. Chmielewski
No one wants to wait around for a Web page that loads slowly, or fails
to load completely. If your site does not respond quickly, you are
likely to lose visitors to more responsive sites. Performance is key
to the success of a site. There are many factors that influence
performance on the World Wide Web, but due to the cooperative nature
of the Internet, most of them are not in any single entity's control.
You can, however, stack the deck in your favor by designing your
pages carefully, and by choosing your Web presence provider wisely.
Here is how to ensure that your pages have the best chance of loading
quickly on a consistent basis:
The Client Side
The client side consists of the end user's computer, modem, Web browser
and connection to the Internet. You can't influence the quality and
speed of the user's Internet connection, but you can lower the time
that it takes for your pages to load. Spend a little time thinking
about your page layout, and ask these questions:
The Server Side
- How many simultaneous colors are you using?
Reduce the number of colors as much as possible. A 24-bit color (~65,000
simultaneous colors) image looks great, but will cause your images to
be much larger than if you dither your graphics down to 8-bits of
color (256 simultaneous colors) or less.
- Are you using the most efficient format for each image?
JPEG is typically good for photographs and other images, while GIF
is well suited to less complex images like logos and line art.
Determine which format produces the smallest file size for each image
on your page. Are you using graphics where text would suffice?
Consider varying the size and color of text using HTML tags instead
of creating your copy with graphics.
- Do you need so many images?
People often create pages with many unnecessary images. This can result
in a 'busy' look, which makes it hard to read. Just as importantly,
it greatly increases the time it takes to load the page. Evaluate
each image based on its contribution ('How important is this image?')
vs. its cost ('How large is this image?').
The server side consists of the hardware, software and Internet
connection of the machine serving your site. You can exercise a great
deal of control over this aspect of performance-by choosing a good
Web presence provider. It is important to consider many points when
evaluating a Web hosting service.
You can read the remainder of this article at CapitalSites, an
authorized dealer of RapidSite, at http://www.capitalsites.com.
- The speed of their Internet connection.
The size of the average Web page continues to increase. Large graphics
and multimedia files can quickly saturate an Internet link, so it is
very important that your provider have a sufficiently large pipe to
the net. The minimum size connection to consider would be a T1 line
(1.544 Mb/s), but this does not give your provider much room to grow.
Keep in mind that it's not just your site that is being hosted, but
many others as well. It is not difficult for a single 'popular' site
to overwhelm the capabilities of a T1. Depending on the provider's
size, a better choice would be to find one with a T3 line (44.736
Mb/s). This will ensure that they will not be running out of bandwidth
at peak traffic times.
- The underlying transport of the connection.
Setting up an Internet link can be a very expensive proposition. Web
presence providers often cut corners and use an inexpensive frame
relay network, or other public type of network, for their 'local-loop'.
This means that your data is sharing communication lines with many
other users before it ever gets to the Internet. It is not unlikely
to experience packet loss due to this type of connection. Make sure
that your provider is connected to the net via a dedicated circuit
for their local loop.
- Number of hops to the backbone.
Traffic on the Internet consists of packets being transmitted from
one router to the next before eventually reaching its destination. It
is not unusual for a packet to be handled by 20 or more routers
before it ends up where it is destined. Each hand-off from one router
to another is called a 'hop' and it has a performance cost. To reduce
the number of hops choose a provider that is as close as possible to
the backbone (the highest bandwidth routes that carry most of the
Internet's traffic). Providers directly connected (1 hop) to the
backbone typically outperform those who are connected further down
stream (multiple hops). Be sure to ask exactly how many hops away
from the backbone your provider is connected. You could also determine
this yourself by using a 'traceroute' program.
First published in WebPromote's Jan. 1998, Vol. 5 newsletter.