Skeleton: adapted for speed, very gracile femur/tibia ratio, its legs are very very slender. It had interlocked metatarsus for enhanced speed, some fast species of dinosaur were bit and healed from trex attacks (ceratopsians)
university of manchester 2007 threw specifics into a super computer about dinosaur anatomy and estimated speeds for trex based on dinosaur anatomy (rarely done) they calculated it was fast. “such calculations can accurately predict the top speed of a 6 tonne chicken but dinosaur’s aren’t built like chickens nor do they run like them”(other methods)
anyway the super computer made accurate predictions when fed info on modern animals.
Trex skull was full of sinuses that made it light/strong, air cavaties. You can see them in CTscans. Big part of its brain dedicated to true binocular vision (used by predators in CHASING. ) and hearing… to see/hear from far away. If it was so slow what is the point of all the adaptations for chasing?