A court described as fast or slow is not being judged impressionistically. Pace is a measured property, and tournaments set it deliberately when the surface is laid.
What pace actually means
Court pace describes how much horizontal speed a ball retains after bouncing, which depends on the friction between the ball and the surface.
A high-friction surface grips the ball, converting forward speed into upward speed, so the ball sits up and arrives slower at the opponent.
A low-friction surface lets the ball skid through, keeping it low and fast, which shortens the time available to prepare a shot.
How it is measured
Testing involves firing balls at the surface at a controlled speed and angle, then recording the outgoing speed and angle with high-speed cameras.
The results are combined into a single rating, and surfaces are grouped into categories from slow to fast on the basis of that figure.
Because the test is standardised, two venues on different continents can be compared directly rather than through the impressions of players who have visited both.
What changes the number
Hard courts are built from layers of acrylic paint mixed with sand, and the quantity and grade of that sand is the primary control on friction.
More sand and a coarser grade produce a rougher surface that grips the ball, while a smoother mixture lets it slide through.
The base beneath the paint matters too, since a cushioned layer absorbs energy and lowers the bounce, which affects how the court plays independently of friction.
Why tournaments adjust it
Organisers choose a pace that suits the event they want, and a slower surface produces longer rallies, which many consider better viewing than a succession of short points.
Scheduling also enters into it, because a slower court lengthens matches and a series of long matches complicates a tight tournament calendar.
Adjustments are usually gradual, since a large change in one year would disadvantage players who prepared for the conditions of the previous edition.
What players notice
Players read the surface within a few games and adjust court position, standing further back on a fast surface and further forward on a slow one.
Ball choice interacts with the surface, since a heavier ball fluffs up and slows down in the air, compounding the effect of a high-friction court.
Complaints about conditions usually concern this combination rather than the court alone, which is why tournaments treat surface and ball as a single decision.
