Yes — I performed 10+ speed tests with Tor, and it always slowed down my original speeds by 98–99%, which is a lot. It usually took up to 5–10 seconds for most websites to load.
Tor’s speeds are really slow because it encrypts your traffic multiple times. Each layer of encryption increases the time it takes for data to travel between your device, Tor’s servers, and the sites you access.
In addition, Tor’s server network is pretty overloaded — at the moment, there are only around 8,000 Tor servers, which are not really enough for the 2+ million people that use Tor.
There’s not much you can do to speed up Tor, so I recommend only using it to browse basic websites — I advise against using it to access sites that host tons of multimedia content, or to binge-watch HD videos.