What Is Website Speed and Why is it Important?
Site speed is the time it takes for a web page to load and become usable by visitors. It's hard to assign a specific number to page speed, as many metrics capture page load factors in different ways and for different purposes. However, a simple metric of page load is the number of seconds it takes until a page loads and is fully displayed in the user’s browser.
Over the past two decades, web performance has become a critical success factor for online properties. Many research studies showed that site speed has a major impact on website engagement, conversion, and revenues. The reality is that today’s web visitors are not prepared to wait, and will easily switch to a competing website if pages load slowly.
Site speed also has a large impact on search engine optimization (SEO). Google, the world’s biggest search engine and a major source of traffic for most sites, uses mobile page speed as a ranking factor. Google also introduced Core Web Vitals (CWV), a set of additional metrics that measure how fast users can interact with a web page, and also impact a website’s search running.
In this article:
- Common Reasons for Slow Page Loading
- How to Test Website Speed?
- Website Speed Optimization: How to Improve Site Speed
Common Reasons for Slow Page Loading
Server response time is a measure of how long it takes the browser to load HTML code when the page is first rendered on the server. Ideally, the server response time should be less than 200 ms.
Following are the most common reasons for slow server response time:
- Inefficient application logic — for example, non-optimized database queries and redundant control flow in the code can needlessly delay user requests.
- Insufficient hardware resources — the server’s central processing unit (CPU), random access memory (RAM), or storage may be insufficient to handle the current loads.
- Insufficient bandwidth — the server may not have sufficiently fast Internet connectivity.
- Server malfunction — problems with hardware or software deployed on the server may result in delays or downtime.
If one page redirects users to another page, site visitors have to wait longer for the request and response cycle to complete. Redirects are a good practice when content has moved elsewhere, or in cases where entire websites are migrated to a different server or domain. However, when redirects are not absolutely necessary to maintain the user experience, they should be eliminated because of their negative impact on performance.
Image file size affects loading speed and quality. Content can be downloaded and rendered faster if a page is delivered with fewer bytes. This is especially important for mobile users who typically have more limited bandwidth. Modern websites make extensive use of rich media such as images and videos.
This makes it important to optimize images—for example, convert an image into a compressed file format or reduce its size. Another important strategy that can improve website speed is delivering rich media over a content distribution network (CDN), which caches content in a geographical location near to the end-user.
Related content: Read our guide to image CDN (coming soon)
Web Hosting Service
Poor web hosting can cause slow page loading. Many websites are hosted via inexpensive, shared server hosting plans, but while these have an attractive price, they provide low and sometimes unpredictable performance.
For smaller websites or those created for personal use, these hosting packages may be appropriate. But for commercial websites, especially those that generate revenue for their owners, it is important to consider high-end hosting services that offer guaranteed service level agreements (SLAs). At a larger scale, website owners should consider a dedicated server.
Modern web pages consist of hundreds of resources, including scripts and CSS style sheets. Each of these resources requires an HTTP request from the web browser to the server hosting the resource, which increases overall load times. To improve performance, developers should aim to minimize the number of resources required to load a page and reduce the number of HTTP requests. Speed tests can help determine which HTTP requests are taking a long time and optimize them.
How to Test Website Speed?
There are various tools available for testing website speed and other performance indicators. Some tools only analyze web pages and show the test results, while others can also generate recommendations to improve performance.
Popular website speed testing tools include PageSpeed Insights by Google, GTMetrix, and Pingdom. These free tools offer insights into website performance and programmatically generate scores and suggestions.
Here are key features website speed tools offer:
Performance bottlenecks monitoring
Website speed tools generate performance scores based on standards that measure web page performance and user priorities. It involves checking resource caching, data download and upload size, client-server round-trip times, and various rules that impact website speed.
Website speed tools generate suggestions to improve page speed, indicating specific performance optimization actions, for example, compressing a large image file currently served uncompressed.
Website Speed Optimization: How to Improve Site Speed
Here are key best practices you can use to optimize your website for performance.
Learn about these and other website optimization techniques in our guide to website optimization (coming soon)
Lazy Loading Images
Images are an important factor in website loading speed. An important way to speed up page load is to defer off-screen images. This is known as “lazy loading”—loading a resource only when it enters the user’s viewport. It is the opposite of “eager loading”—loading all web page resources immediately when the page is accessed, which is the default for most web frameworks. Lazy loading can be effective not only for images, but also for other resources that are not needed to render the currently visible portion of the page.
Optimize Delivery of Cascading Style Sheets (CSS)
Content delivery networks (CDNs) maintain cached versions of content in different geographical locations called points of presence (PoPs). Each location has multiple cache servers that serve content to visitors from that location. This means the content is stored closer to the user, response times are reduced, and page load time substantially improves. Today CDNs are easy to implement and are provided out of the box by many hosting and cloud providers.
In many cases redirects are performed unnecessarily—for example, when an internal page has moved, and other pages continue to link to its old location, instead of updating them to point to the new address. The best practice is to always update web pages to link to the current address of other pages. A web crawler can provide a list of all pages on a website that link to redirected URLs.
Another common problem is chained redirects—a page links to an address, which redirects to another address, and possibly further to other addresses. Here the fix is to link directly to the final resolved URL, which can significantly reduce page load time for users who follow the link.
Remove or Optimize Plugins
Modern content management systems (CMS) support plugins, which can be highly useful for website owners. But many plugins also have a negative impact on page performance. If too many plugins need to be loaded, specific web pages or the website as a whole might slow down significantly.
It is important to evaluate plugins carefully and remove old, unwanted or ineffective ones. Even for the plugins a website really needs, it is important to select those that have the smallest possible impact on performance.
To see which plugins have the greatest impact on your site's performance, selectively disable each one and measure performance on important pages. Although this is time-consuming, it will help you identify the “offending plugins” that are significantly hurting performance. Alternatively, some website performance scanners can automatically analyze plugins and generate a performance report for all plugins on a website.
Optimize Images and Video
Optimizing the media displayed on your site goes a long way in ensuring visitors will find it on a search and, once they’re there, engage meaningfully.
To adopt automation capabilities and streamline your media-management workflow, consider a tool like Cloudinary’s Programmable Media, which optimizes both the quality and file size of media assets for automatic delivery, all without coding or manual work on your part. Plus, Cloudinary’s optimization technology can monitor media performance in a central hub for collaboration, ensuring the continued progress of your team’s web-performance enhancement and SEO efforts.
Check out Cloudinary’s Programmable Media in action and start planning for performance improvements for your web-based media.