I’m looking for a reliable way to test the speed of websites. I was recommended different tools by different sources. The problem is those tools (Google Page speed Insight, GTMetrix, Pingdom etc.) are showing very different results. To some extent it is expected since they are testing from different locations, using different infrastructure and different browsers. Yet it still leaves us with a dillema - How to test (Perhaps including A/B test) the speed of the website? Which speed test tools are trustworthy and relevant?
Any suggestions or thoughts on the matter?
I've had this same problem, when I've tested a client's website using one tool, but then they test it with another and query why the results are different.
I think the simple answer is to pick one tool that you like and stick with it, and don't use other tools. Personally I prefer Pingdom.
Also, one test is never reliable. One test might load much slower than usual. That's why I test five times and take an average.