What is the difference between load testing and performance monitoring?
By Viktor Petersson
Load testing and performance monitoring are both techniques used in order to provide better and more consistent user experiences on websites. They do however serve very different purposes and are likely to be used by different teams, for different goals. This article will be walking through some of those differences in order to help you establish which one is the most relevant for your use case.
Performance Monitoring, also known as Web Performance Monitoring, is a technique that seeks to measure and help optimize the speed, usability and user experience for a specific use case or user. Though several different situations and combinations of factors may be simulated and evaluated, the data points are connected to a single situation at a time. An example of this would be testing the speed and user experience of a website loading for a user who’s on a mobile device, on 3G, in North America.
Siteimprove Performance is an example of a tool that helps with this, by allowing users to simulate different visitor situations with a range of parameters (device type, network speed, location, etc.).
In doing so, it becomes easier for you to pinpoint which use cases you want to target and optimize, in order to provide even better digital experiences on your website.
Load Testing is a technique that aims to measure the robustness of your website, how this degrades given different amounts of concurrent loads and where the limits are in terms of overall load. There are several tools that perform load testing by continuously increasing the number of requests for a specific page or service, in increments, up until a certain threshold of wait-time is reached. At this point, the page is considered unresponsive and the experience on the page has degraded.
This allows you to determine the concurrent load capacity of a site’s infrastructure, which is useful for cases in which you know there are sporadic variations in the number of requests and sessions being handled simultaneously. Examples of this include online shopping sale day, exam results days or ticket releases – all cases where traffic, load and requests tend to spike for a temporary period.
How do I know which solution I need?
Although these techniques may seem similar at first, they actually serve quite different purposes and are typically used by different users.
Web Performance Monitoring is typically used by marketers, web developers, performance optimization consultants or webmasters in order to optimize the user experience so that you easier reach your digital goals. These goals can include increasing conversion rates, reducing bounce rates and many more. You can read more about this here: What is Performance and why does it matter?
Load Testing is typically done by IT managers, infrastructure engineers and backend developers. The purpose here is often to ensure that the site is capable of handling incoming traffic at all times and that it can fulfill these requests in a timely manner. It can also be useful to help predict traffic spikes, which then allows the IT team to better prepare for these.
In short; Performance Monitoring measures how well your pages perform for a single user, and load testing measures the capacity of concurrent users.