A really good example here of how testing using the web browser, especially on lower spec machines is not accurate enough with higher speed connections. 

This is from a HP AMD A6 notebook - about 4 years old. Has 8GB RAM & a SSD. Isn't the most powerful thing, but is fine for basic light use. 

This first test is from the web browser on a Gigabit connection

And this second test is from the speedtest app. Tests done to the same server, one directly after the other, with the notebook otherwise idle.