http://rzuwtppveur6yh3n2in7trmddgrkuhww4eb2znykgjwubihfpljiyuid.onion
You can help improve the speed of the network by running your own relay , or encouraging others to do so.
For the much more in-depth answer, see Roger's blog post on the topic and Tor's Open Research Topics: 2018 edition about Network Performance.
You can also checkout our recent blog post Tor Network Defense Against Ongoing Attacks , which discusses the Denial of Service (DoS) attacks on the Tor Network.