NONE of the classics runs at 60 fps on any platform. All at 30fps (or 25fps for TR1 PSX PAL version - don't know about Saturn)
However TR5 does use floating points instead of integers for 3D coordinates, so it results in a smoother feeling (points don't snap to the closest full number).
Here's a comparison video:
TR4 vs TR5: Integers vs Floating points
You can see how Lara moves smoothly in TR5, but in TR4 it's more jerky. You can even see her butt "going in and out" as she breathes.
This also applied to cameras and everything that has coordinates.