These metrics analyse the "T Done" timing for the browser. This is when the page is deemed loaded.
Median Page speed is the median T Done measurement within any minute.
Mean Page speed is the average T Done measurement within any minute.
95th percentile shows the T Done measurement below which falls 95 per cent of T Done measurements in that minute.
We focus mostly on the median and 95th percentile measurements as this is a good indication of the target user experience for any website. There will always be outlier measurements above the 95th percentile which drag up the mean score. Often, it is not possible for websites to improve the experience of the users above the 95th percentile as these users may be subject to very poor Internet connections, poor browsing equipment or be in locations which make reaching the user with pages in a timely fashion commercially infeasible.
Page Speed will often vary over time and time of day subject to factors such as;
- The amount of traffic on the website (too much and too little)
- Changes to the website itself (addition or deletion of content from the pages)
- Changes in the browsing patterns of users (to or away from slower or faster pages on the site through marketing campaigns etc)