eliminate MacBook CapsLock delay

On my MacPro there is one issue (and guys from Apple think this is feature...) that annoys me very much: there is a time delay between CapsLock switching. I used to do that fast. If I go to preferences and reassign caps lock to any other button and then back it works OK then, so it is not a hardware problem.

Is there any way to fix that ?

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.

If you install Karabiner-Elements, it defaults to zeroing out macOS's obnoxious caps lock delay.

The version you need to install depends on your macOS version.

macOS 10.15.6 and above

Download and install Karabiner-Elements 13.3.0 or higher.

macOS 10.11 through 10.15.5

Download and install Karabiner-Elements 11.6.0.

(Note that Karabiner-Elements 12.0.0 - 13.1.0 re-added the Caps Lock delay, and 13.3.0 isn't available on older OS versions.)

This is the only solution I know of that both works on 10.12 and requires nothing more than installing & running an application without any special steps or reconfigurations.