Web performance optimization is crucial for the success of any online business. However, starting from its definition, the topic brings with it elements of complexity: what does the performance of a website consist of? Which indicators have a real impact on the business and, therefore, must be constantly detected and monitored? 

Web performance and the most effective KPIs 

Depending on the type of activity and the business model, web performance can be represented by indicators such as: 

• in-target traffic that the site is able to generate; 
• unique users it attracts through marketing activities; 
• time visitors spend on the pages; 
• conversions generated by marketing activities; 
• the authority of the site and positioning in search engines. 

The universe of web, digital by definition, can count on a vast ecosystem of performance indicators, the selection of which depends on the business objectives that the company sets itself. 

An e-commerce will focus its attention on conversions; an online magazine will be more attentive to traffic, time-on-page and bounce rate; a company in full expansion strategy towards the Chinese market (for example) will evaluate the traffic increases coming from a certain geographical area. 

Understand the causes and act accordingly 

We live in an era driven by data, of which the web is the first major manifestation. Compliance permitting, any element of the online experience can be monitored, evaluated, and investigated. For this reason, after identifying in the first instance which KPIs to monitor, companies have the burden of tracing the causes of the surveys, both positive ones and – more frequently – those that need corrective action. 

So why is the time-on-page low? Why does traffic suffer strong dispersions in the e-commerce purchase path? Why is the site not positioned like the competitors despite the investments in advertising and in the quality of the content? Clearly, it is not possible to give a single answer, but it is precisely from the selection, analysis and integration of different KPIs that companies can understand where to intervene with targeted activities. 

By way of example, social activities or the advertising  could drive non-target traffic to the site, in this case the internal user experience (on-page)  can be highly improved, by improving the copy and  SEO activities. 

Technical KPIs and their impact on web performance 

In the world of web performance, there is an area on which the attention of all companies is concentrated: that of technical KPIs. In this context, the expression web performance has a unique meaning: the ability of the site to guarantee availability 24/7 (uptime) and to provide the visitor with the content he wants in the shortest possible time, regardless of the device used and the  geographical location of the user. 

There are at least two main reasons why site performance should be fast in satisfying user requests: the customer experience and the positioning in search engines. The first is easily explained: in a web landscape that makes 24/7 availability and fast page speed opening its strong point, introducing a delay (latency) between the request and the rendering of the page increases the bounce and leads customers (actual and potential) away to the competition. 

The second factor depends on Google’s indexing policies, which are strongly influenced by the technical performance of the site, and in particular by page speed, an indicator that can be easily monitored with the tools made available by the company. The topic of optimization is extremely complex, and is beyond the scope of this article. 

So what are the main technical KPIs that affect web performance? The following list of technical KPIs are valid regardless of the type of business and its objectives: 

Page Speed 

Measure the page loading time starting from the user’s request. 

It is the sum of three elements: 

• the server response time (TTFB, Time to First Byte)
• the data transfer speed, 
• rendering times on the browser. 

It depends on many factors, including content optimization and the use of one or more Content Delivery Networks (CDNs). 

Time to interact 

Given the centrality of engagement, companies must accelerate the time that elapses from the request for content to the possibility of interacting with the page, from a simple link to a contact form. 

Requests per second 

It is the amount of requests the server receives every second. Beyond a certain threshold (which depends on each case), performance begins to deteriorate and traffic balancing and bandwidth management strategies must be adopted. 

Time to First Byte (TTFB) 

This is the time from the request to the receipt of the first byte of custom content. Current websites are heavily based on dynamic content, so the TTFB measures the server’s ability to generate custom content and transmit it as quickly as possible to the user’s browser. 

Error rate 

Measure the number of server-side errors in a given timeframe. It is especially useful for analyzing trends, for example in relation to traffic peaks (promotions, events, certain periods…). 

The above list is certainly partial, but it is intended to be a useful starting point for keeping web performance under control, considering the strong impact of technical parameters on business results.