Updated: January 2018
Never trust speed test scores. Ever. Always measure improvement in milliseconds of load time.
How to interpret pingdom.com and webpagetest.org speed test results.
First byte or Time to First Byte (TTFB) – Delay between the first HTTP request from the web browser and the reception of the first byte of the web page by the browser. It’s recommended a time less than 200 ms. It’s a server delay. You can’t fix TTFB except by changing hosts or upgrading services. $$$
Load time – The web page is fully loaded, all the resources are fetched, parsed and executed. Pages must loaded within 4 seconds. We always shoot for 2 seconds but under 1 seconds loads gives us goosebumps. At 10 seconds, people are long gone.
Page size – The total size of assets loaded: CSS, JS, HTML + other (like scripts, images, ads, etc) Also called page weight and is expressed in “k” or “M” bytes.
Page score – The score calculated based on a number of factors: compression of the resources, enable/disable caching, CSS/HTML/JS minifying etc. Score is irrelevant.
UNDER 9-minute video:
And this link helps:
Pingdom.com is for quick-and-dirty best-case scenarios. First test is unprimed cache and second test (click again) is primed (faster).
WebPagetest.org is for worst-case scenarios. It’s more reliable but takes longer to test.
Never evaluate with Google PageSpeed Insights. WordPress can’t pass their criteria. Google doesn’t even use that data for ranking anyway. They have people chasing their tails.
Most site owners and developers just don’t test plugins. They rely on popularity numbers. Moo! Herd mentality.
For example, iThemes Security and WordFence are both popular security plugins. That’s an immediate red flag that they’re slow. Why? It’s crazy. But the speed results for popular plugins always turn out slow in tests. Same for themes. People just go for the heavy plugins loaded with the most features. Overkill. The herd starts following the path thinking active installs must mean goodness. Nope.
Researching plugins on the 52,000 plugin directory is difficult and tedious. We’ll keep researching and testing plugins and themes for improving speed benefits for your sites.
Mobile WordPress Speed – without coding!