Tried it and compared to Ookla speed test. The results were competely different.
Looked at the reviews and immediately deleted this.

This addon tries to trick the user into switching search engines, additionally, it disables Ublock Origin once installed and tries to serve a host of ads into the browser.

This is malicious, please don't install.

This Ext is lame. It wants to change your default browser to Yahoo, and when you don't, it doesn't work.