Gave it a try a few months ago. Slow as molasses, even on 200+Mbps connection. I know it's because of the encryption and the hopping, but it was quite unusable, in my opinion.
Just downloaded it again.
fast.com without Tor for me = 220-230 Mbps
fast.com with Tor for me = 3.0-4.0 Mbps
Would love to use it more regularly, but the slowness speed makes it way too prohibitive.