Question: 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 ?

Answer: 
If you want a simpler solution than Karabiner, I've written a very small, open source tool to fix exactly that.

<https://github.com/gkpln3/CapsLockNoDelay>
I had exactly the same problem,
I could solve it by installing **Karabiner-Elements** and
making the following modification :

* select the Simple Modifications tab
* add a new modification (Add Item)
* and put **from key** `caps_lock` **to key** `caps_lock`

[![enter image description here](https://i.stack.imgur.com/bk9LQ.png)](https://i.stack.imgur.com/bk9LQ.png)