See "cycle journey planner" button at top of page.
"We’ve rolled out an improvement to the journey planning engine which should mean it returns the route solutions about a third more quickly than before.
It’s still not as fast as we would like, but we have plans to make a major change this coming month or so which we believe will make a much bigger difference."
More -http://www.cyclestreets.net/blog/2010/04/02/ramping-up-planning-speed