It's about as fast as mundo's, maybe even a bit faster but it does a LOT more damage and you don't use hp to clear (plus if you've ever played udyr top you know how scary early game tiger is for 1v1s). Mundo does a pretty large amount of damage himself while still being tanky, but building this makes your early-mid game much stronger. I think they're pretty similar late game, though I would admit mundo wins, but early game your ganks are SO much stronger that you win easily during that time as you're building really tanky without sacrificing any damage, even if you don't build the standard wit's end until later. They can't really just ignore you either, as with this you can walk into their team, randuin's and then bear all of them and just cause havoc with tiger/phoenix.
On the other hand, mundo has one of the best if not THE best transition from early to late of junglers in this game, so yeah :P
Oh, what are they going to do when the lights go down
Without you to guide them all to Zion?
What are they going to do when the rivers overrun
Other than tremble incessantly?
High is the way, but all eyes are upon the ground.
You were the light and the way they'll only read about.
I only pray, Heaven knows when to lift you out.
Ten thousand days in the fire is long enough;
You're going home.