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Testing Web Performance by Throttling Bandwidth

By November 21, 2010October 20th, 2012Development, Recommendations, Tips & Tricks

In the past, I often found myself wondering how some of my websites would perform when accessed from a low bandwidth connection. Unfortunately, I had no convenient way to test such a scenario, so I usually just forgot about the idea. I recently found myself in a similar scenario at work, and my searches returned a useful tool, Speed Simulator, by Vikas Patial:

Speed simulator is a simple throttling proxy which allows you to see how your site behaves under different connection speeds. It was written by me to test AJAX/Flash loaders and see how much my time took to load. You can simulate various speeds like that of a modem or a ADSL. A pre delay function is also there to help simulate delays due to DNS, connection establishment etc.

Here’s what it looks like:

Screenshot of the Speed Simulator user interface

It simply acts as a proxy, so all you need to do is point your browsers to access the web through Speed Simulator. You’ll then be transported back to the good ol’ days where most people had to wait for websites to load.

To do this:

  1. Click Start, and search for “Internet Options”. Launch it.
  2. Click on the “Connections” tab.
  3. Click the “LAN Settings” button, found within the “Local Area Network (LAN) Settings” section.
  4. Once the “Local Area Network (LAN) Settings” dialog appears, locate the “Proxy Server” section.
  5. Enable the “Use a proxy server for your LAN” checkbox, and enter the following:
  • Address: localhost
  • Port: 8080 (reflect the port listed in Speed Simulator)

Local Area Network (LAN) Settings dialog in Windows, with a proxy server configured.

Press OK to save your changes, and then simply click “Start” in the Speed Simulator window.

That’s it – all you need to do next is launch a browser, the bandwidth should be throttled. I’ve seen it work with Google Chrome and Internet Explorer. Configuring a proxy in Firefox requires different steps, but should work just as well, once configured.

I can see myself using this tool in the future, and not only for simple performance tests. For example, I can use it to test for possible timing-related flaws in JavaScript code. Definitely a welcome addition to my web development tool set.

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