Magento Response Time, Server Latency and Time To First Byte
The response time of websites matter for website visitors, for customers and for conversion and is popularly referred to as the Time to First Byte. Contrary to what most believe, caching is not what determines the performance of your website – or at least not the way you expect it to.
The Time to First Byte (TTFB), or server latency, is the name of the delay starting when you click on a webpage, and until the first byte is received over the network. A low TTFB gives the site visitor the feeling of instant delivery of a web page when something is clicked.
This test is focused on TTFB, and the results do not tell anything about the scalability and max capacity, or the front-end performance of the tested sites. However, a high TTFB tells us, as hosting professionals, that scaling the site will be much harder – and that the performance and experience for the end user is bad.
Common for all the stores we have tested is that they have quite a bit of traffic. Therefore we would expect the sites to be properly set up and perform well when tested for performance.
Magento Performance Test Objective
The main aim of the test is to collect response times, distribution of response times and information about how well full page caching is working for performance. The results will give an interesting perspective on the user experience for store visitors.
We have tested the performance of 15 popular Magento E-commerce sites, hosted by different companies on various locations in Northern Europe.
The following graph is an example that shows the distribution of response times like one would like them to be (KariTraa.com). The majority of requests in the initial test are delivered under 1 second, and a few requests within 2 seconds.
The consecutive cache test shows that full page caching is working for close to all requests, which tells us that sudden high traffic would be dealt with smoothly.
The graph below is an example of an equivalent test as above (Hoyer.no), but with results that tell us that users are getting a very bad experience. Only a small percentage of requests are served under 1 second, and the large majority is served in three seconds or more.
The distribution in the cache test also suggest that full page caching is in use, but for the large majority of requests – not working. Sudden high traffic to this site would most likely render it unavailable, because the backend resources would be spent delivering mostly uncached requests.