Third Parties and Single Points of Failure

Summary

You’ve heard it many times – third party content can easily cause an otherwise well performing website to become sluggish and slow. And depending on how this content is loaded, it can also introduce single points of failure (SPOFs). When a large cloud provider or content delivery network (CDN) experiences a disruption, their impacts are felt across the world and often trigger headlines about the many websites that were affected. However, there are numerous secondary impacts triggered by third party content, which can be disruptive even to companies that don’t use the affected provider. In this blog post I’ll discuss some of the performance and availability risks associated with third party content and how you can test for these single points of failure (SPOFs) on your websites. I’ll use HTTP Archive data to explore how many sites could be at risk and RUM Archive to get a sense of how prone to slowdowns some of these third parties are! Third Party Failure = SPOF A third-party single point of failure (SPOF) can occur when a website depends on an external service for critical or render-blocking resources. If the third party content fails to load, then the page load may be stalled until the request times out. For example, in the two filmstrips (taken from a WebPageTest private instance) you can see how a failure of a third-party affects the user experience. The SPOF measurement in this example simulates what a client would see if a render-blocking third party, such as a consent management service, became unavailable. In this case, the user would essentially see a blank screen until the third party request times out. Most recently, people have been noticing SPOFs due to outages experienced by large cloud providers and CDNs. For example, a major CDN recently experienced a few high profile outages and many of their customers were impacted. However, many sites that don’t use their services directly were also affected due to third party content that was being delivered throu...