Mac keyboard caps-lock delay

I was running the latest firmware on an Apple 2007 Aluminum Wireless Keyboard, and MacBook Pro Keyboard, but the issue still persisted. However, oddly this fixed it:

1. Open System Preferences
2. Click Keyboard
3. Click Modifier Keys…
4. Select your keyboard from the Select keyboard: list.
5. Set the Caps Lock Key: to No Action.
6. Press OK.
7. Ensure your Caps Lock no longer works on your keyboard.
8. Click Modifier Keys… again.
9. Set the Caps Lock Key: to Caps Lock.
10. Press OK.

Now, the Caps Lock key works instantly for that keyboard. Repeat as-needed for each keyboard you own.

Source : prosoxi[dot]com