Changing the keyboard repeat speed in macOS makes held keys react faster during editing, navigation, and cleanup work. A quicker repeat rate is especially useful when holding Delete or the arrow keys in long documents, terminals, or code editors where slow repeats turn small corrections into repetitive hand movements.
macOS controls this behavior with two linked settings in the Keyboard pane. Key repeat rate sets how quickly supported keys repeat after repeating begins, while Delay until repeat sets how long the first pause lasts before the repeated input starts.
Current macOS releases place these controls in System Settings → Keyboard. Macs that still use System Preferences keep the same controls under Keyboard there. The change applies immediately, so testing in TextEdit or any other text field is enough to confirm the new behavior.

Keep the slider to the right of Off when the goal is faster repeated input instead of disabling repeat.

The new setting takes effect immediately, so no restart or sign-out is required.