I think it's heavily dependant on the site you're using. Loading this page in Firefox on android with a pretty crappy connection took ~2 seconds. In the Tor browser it was ~6seconds
Definitely slower and this is a pretty minimal page, but I've got a hunch it really starts to choke when a page is loading a ton of different css/js assets at load
What's still often slow in Tor is making initial connections to hidden (onion) services. Last year during a DDoS attack on Tor this was unreasonably slow and took minutes or more, at which point sites just appeared broken. Once connected, though, it would still work pretty well. So if your experience is using Tor to access onion services you might have an inflated idea of its slowness for normal purposes.
Visits to normal websites were only somewhat affected and were still pretty reliable.