URL Shorteners & Page Load Speed

Danny Wahl's picture Danny Wahl  •   •  DevOps

URL shorteners are all the rage right now. They make it easy to share links in sites like twitter without blowing your character limit. They make sharing gross long urls easy in email (for the bulk of users that don’t know how to use an <a> tag or a “link” button). And some even offer cool analytics on the back end. They seem like an all around good idea because who wants to see this:


When you could see this:


But we also know that there’s a good push towards minimizing page load speeds, so I’d like to take a look at whether or not the URL shorteners are worth the time. What I’ll outline here is an emulation of a real-world example I came across while riding the bus home from work. The emulation will not be extremely scientific but I’ll examining the overhead from a shortened link shared on twitter. Now link shortening is unavoidable when sharing something on twitter because all links are filtered through t.co

Twitter uses the t.co domain as part of a service to protect users from harmful activity, to provide value for the developer ecosystem, and as a quality signal for surfacing relevant, interesting Tweets. Read more

So, on to the experiment. We’re going to take a link to this post that you’re reading right now and:

  1. Get the RSS feed url
  2. Pass it to goo.gl URL shortening service: http://goo.gl/bmTwkE
  3. Pass that to ow.ly URL shortening service: http://ow.ly/p99kM
  4. Pass that link to our tweet

Once that’s live we’re going to start profiling in in firebug and then we can see our results. Now I know what you’re thinking: Why share a link to the RSS feed? It’s a dumb idea but like I said, this is an emulation of a real-world experience. So here are the results:

A small note, I was having trouble (read: I’m lazy) documenting the profiling info for t.co, but it was consistently coming in around 200ms. Also, the info above is from 3 separate tests, but they were all about the same results. Now current studies show you have about 3 seconds to load your page, and by using URL shorteners you’re potentially risking using up to a full third of that time just redirecting the user. “But redirects aren’t actually my page loading” one might say. Yes they are to the end user. From the time I click a link, I’m loading your page. I don’t care if the jQuery CDN is down or Google analytics is slow to load, it’s your fault (and rightly so).

Let me paint the picture a little worse for you too. This test was done on a 40Mbit fibre connection. Not an hspa or 3g mobile connection. Sure it’s only 2 extra “get”s but remember this, it’s also 2 extra DNS lookups. The amount of info that we’re grabbing is extremely small (20bytes) but DNS lookup times can vary wildly.

Look at the results again, another thing to take into consideration is that it’s possible all url shorteners are not created equal. Surely Google has a greater infrastructure than twitter or ow.ly and the results bear that. Could it be that I’m in a place with a longer round trip to the ow.ly servers? Most definitely so, but as a user, I don’t care.

So, in the end, I have to suggest this: If you don’t need it, don’t use it. Which is probably pretty good advice for the whole of web development.

On a final note I’d like to point out that not all internets are created equal. bit.ly and ow.ly are blocked in mainland China (where I am) by the Great Firewall. There are many websites besides twitter where users or admins rely a lot on these services unnecessarily. By unnecessarily I mean that there are probably alternative methods of achieving the desired functions (analytics, malware scanning) that they’re serving.

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