Smaller and thinner is always more agile.
Less fat and smaller internal organs also help - at the cost of endurance and ability to use low-energy foods.
Bones should be lightweight and not too easy to break - so fill them with some air, like a bird's bones. Even if that means broken bones require longer treatments.
Some of the brain could go down into the spine (as with birds again) - especially anything related to motoric abilities. Improves reflexes, allows for a smaller head without reducing intelligence and strengthens the spine without adding unnecessary weight.
Stealing photosynthesis from the plants (ideally black, brown or red ones, as green is not a cat-like color) helps to recover strength while resting, even if it only makes a small percentage for a warm-blooded being.
Some animals like Kangurus can 'spring-load' their muscles. This allows jumping around without using a lot of energy.
The larger the frame, the more the bones need to support the muscles - make bones near important muscles across joints extend a little bit for a better angle the muscles can use. Muscles can overlap by splitting the extension into a Y-shape on one side, which also stabilises the joint. Only works for joints limited to one direction, like knees or elbows.
A muscle along the back could help go quickly from a crouch to a jump, or from absorbing a landing on two feet to jumping again. Useful as your 'cat' will usually not use all four paws for movement, I assume.
The hind legs can be a little short for a human - allows switching to running on all fours if needed, for extra-fast sprints. Here, the strengthened back muscle will also add to the speed.
A relatively long neck will help move between upright and quadropedal movement, and also be good for fast jabs - like a snake or a bird.
4 or 6 small boobs are better than 2 large mammaries. However, if you want your cat-woman to be sexy for humans, use the place well - fat, water and oxygen storage, for energy, dry spells and diving, respectively. Similar to some animals expanding their throat, your cat woman could then use her mammaries to signal attraction.
Make your tigress cheat a little - shoes with a blade spring each, an elastic climbing rope with knots for easier climbing (shoes should have a small gap between toe and other digits, to make use of this), knee and elbow protectors for wilder maneuvering, a flight suit for jumping from large heights and other such accessories.