From an entry (which includes references here omitted) in Döderlein's Hand-book of Latin Synonymes:
Citus; Celer; Velox; Pernix; Properus; Festinus. 1. Citus and celer
denote swiftness, merely as quick motion, in opp. to tardus, ... velox
and pernix, nimbleness, as bodily strength and activity, in opp. to
lentus; properus and festinus, haste, as the will to reach a certain
point in the shortest time, in opp. to segnis ... 2. Citus denotes a
swift and lively motion, approaching to vegetus; celer, an eager and
impetuous motion, approaching to rapidus. 3. Pernicitas is, in
general, dexterity and activity in all bodily movements, in hopping,
climbing, and vaulting; but velocitas, especially in running, flying,
and swimming, and so forth. ... 4. Properus, properare, denote the
haste which, from energy, sets out rapidly to reach a certain point,
in opp. to cessare; whereas festinus, festinare, denote the haste
which springs from impatience, and borders upon precipitation. ...