tor is slow because therse no anti-spam (actually they added a sort of proof of work client side, but it is not so effective), theres no incentive to run nodes that are the facto moslty feds and volountary. If you add micropayments as spam filter and as economic incentive for people to run relays, you can have a tor network that scales.
Also its trivial to implement in a way that provide reliable anonimity, it just need to reimplement onion routing, all problems in theory are solved.