WebPagetest Forums
Download Speed Comparisons - Printable Version

+- WebPagetest Forums (https://www.webpagetest.org/forums)
+-- Forum: Web Performance (/forumdisplay.php?fid=3)
+--- Forum: Discuss Test Results (/forumdisplay.php?fid=4)
+--- Thread: Download Speed Comparisons (/showthread.php?tid=12293)



Download Speed Comparisons - Don - 05-28-2013 03:57 AM

I am considering an offer from my ISP to double my download speed from 25 mbps to 50 mbps. I used WebPagetest to see whether I would notice any performance improvement with this speed upgrade.

One test was at 25 mbps and the second was at 50 mbps, repeating five times. As a URL I used a page on a website I manage myself, so I know what the content is and that there were no changes during the tests.

To my surprise, not only was the 50 mbps not quicker than the 25 mbps test, it was actually slower: 2.0s at 25 mbps and 2.3s at 50 mbps.

My questions: Is this a fair test using the WebPagetest? If so, what is the message, why does the slower download speed test faster?

Don


RE: Download Speed Comparisons - pmeenan - 05-28-2013 11:05 PM

Depending on how many tests you ran and what the site was, the difference between 2.0 and 2.3 seconds could have been fluctuations in the content itself or response times from various servers. For web browsing, once you get over 3-4Mbps or so then bandwidth doesn't make much difference and pages are more latency constrained than anything: http://pandawhale.com/post/396/more-bandwidth-doesnt-matter-much-spdy-research-paper

Going from 25 to 50Mbps will only show up if you are doing large file downloads regularly (Steam is a good example of a platform that can pretty much use all the bandwidth you can throw at it for downloading games), if you have a lot of people streaming HD-quality videos all at the same time or similar activities that transfer tons of data.


RE: Download Speed Comparisons - Don - 05-28-2013 11:37 PM

Thanks for the informative answer and links.

I guess my confusion was with the IPS's wording " Up to 2x faster speeds". But if I understand the article correctly, they would have to effectively "double the speed of light", so to speak. What they are doubling, apparently, is the bandwidth.

The "superhighway" analogy is also a bit confusing. When they say they are doubling is the "speed", what they mean is they are doubling the number lanes. The speed limit will remain the same. I can't use the additional lanes to carry the more information simultaneously from a webpage, I'm still stuck with using one lane. Am I getting this right?

Thanks again,

Don


RE: Download Speed Comparisons - pmeenan - 05-29-2013 12:36 AM

Yes, when ISPs refer to speeds they are referring to bandwidth. Technically some things will be 2x as fast (downloading files that are a few hunderd MB or bigger for example) but not regular web browsing.

Very good analogy though it's not so much that a web page is just one lane - they can use several. Thing of it more as a highway between Chicago and New York. More lanes will help you get more cars from Chicago to NY over time but for any individual car it still takes the same amount of time to make the drive.