Is a female deer faster than a buck?

A deer is faster. over short distances. However, a kangaroo is able to keep up a sustained, high speed for far longer than any of the animals which rely on four legs for running.

Kangaroos have powerful hind legs ideal for speedy bounding. Kangaroos have large, strong tendons in their hind legs which act as "springs". The springing motion requires less energy than running does, so kangaroos are able to bound for longer distances than other mammals with the standard four legs can run. Their strong back legs and elongated hind feet enable them to bound. Kangaroos are able to travel long distances at a high speed, expending very little energy. They are very energy-efficient, and this is linked directly to the physical action of bringing their hind legs up with each hop. Every hop literally refills the lungs.