We analyzed 5 million desktop and mobile pages to learn which factors impact page speed.
First, we established worldwide benchmarks for TTFB, Visual Complete and Fully Loaded load time metrics.
Then, we looked at how image compression, CDNs and hosting impact site loading speed.
Our data revealed some very interesting (and surprising) insights.
Here is a Summary of Our Key Findings:
1. In our analysis of 5.2 million pages, the average desktop Time to First Byte (TTFB) speed is 1.286 seconds on desktop and 2.594 seconds on mobile. The average time it takes to fully load a webpage is 10.3 seconds on desktop and 27.3 seconds on mobile.
2. The average web page takes 87.84% longer to load on mobile vs. desktop.
3. When comparing major CMSs against one another, Squarespace and Weebly have the best overall mobile page speed performance. Wix and WordPress ranked near the bottom.
4. On desktop, CDNs have the biggest impact on TTFB. However, on mobile devices, the number of HTML requests seems to affect TTFB the most.
5. Overall page size has a significant impact on desktop and mobile “Visually Complete” loading speed. Larger pages take 318% longer to visually load compared to smaller pages. We also found that gzip compression helps images load more quickly on both desktop and mobile.
6. Total page weight is the #1 determinant of Fully Loaded page speed. Light pages fully load 486% faster than large pages.
8. Pages with very low or very high file compression have above-average page speed performance (measured via First Contextual Paint).
9. Third-party scripts significantly slow down page loading speed. Each third party script added to a page increases load time by 34.1 milliseconds.
10. We discovered that using responsive images results in the best overall image loading performance. Use of WebP was significantly less effective at reducing image load times.
11. GitHub and Weebly web hosts have the fastest overall TTFB Performance. Siteground and Wix are the slowest among the hosting providers that we analyzed.
12. China, Japan, and Germany have the fastest TTFB loading times. Australia, India and Brazil have the slowest TTFB times.
13. CDN usage was correlated with worse page speed performance. This is likely due to the fact that certain CDNs perform significantly better than others.
Benchmarks for Key Page Speed Load Time Metrics
Our first task was to establish benchmarks for important page speed metrics.
As you may know, “page speed” is actually made up of several distinct stages.