Improving 3rd Party Script Performance With IFrames

Philip Tellis (Akamai)
Web Performance, Mission City Ballroom B1
Presentation: external link
Average rating: ****.
(4.47, 15 ratings)

We all know the rule. The best way to reduce network latency is to eliminate the network. Resources read out of a browser’s cache typically load up in 0-1ms. Setting your resource’s max-age to a very long time (like 10 years) tells the browser that this resource is never going to change. But as web developers, we also know that everything changes.

The common solution is to use versioned URLs. When a resource on the server changes, simply change its URL and the browser will load up the new version. This has two problems. Third-party widget providers cannot expect all of their customers to update all of their pages every time a change is pushed out. Even if they could, if the change is a critical security issue, there may not be enough time to wait for everyone to update their URLs. It also means that the browser uses up more of its cache, since it’s now holding on to an old cache entry that will never be used. This entry will eventually be purged by the LRU algorithm, but until then it takes up some space.

The solution, is to use a self-updating script with a far-future expires header.

Third-party scripts also have another problem. Unless they’re loaded after the onload event fires, they will block onload, and this could have a negative impact on page performance.

In this talk, we’ll discuss the code to load up a script in parallel with the page without blocking onload, and then the code to get this script to self-update when required.

We’ll cover all pre-requisites for such a script, and all issues that we’ve noticed while running this in production at LogNormal for several months. At the end of this talk attendees will have everything necessary to decide if they need to use these techniques, and how to do so if they do.


Photo of Philip Tellis

Philip Tellis


Philip Tellis is a geek who likes to make the computer do his work for him. As co-founder and CTO of LogNormal, he analyses the impact of various design decisions on web application performance, scalability and security. He is also the lead developer of “boomerang” — a JavaScript based web performance testing tool.

In his spare time, Philip enjoys cycling, reading, cooking and learning spoken languages.

Philip has spoken at several conferences in the past, including FOSS.IN, FREED.IN, Ubuntulive, Linux Symposium, PHP Quebec, ConFoo, FOSDEM, IPC, WebDU, Velocity and JSConf.


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