Ok I'm back with more testing.
As advised, I installed Wise Care 365, and here are the results.
WB_OFF
WB_ON
As you can see, boot time is 32 seconds with WB on or off, but these numbers don't represent the actual boot time, as you can see in the previous video that I've uploaded.
But don't focus on that, as I did more tests.
I have installed the original SSD that came with the laptop, which contains clean Win10 with standard Dell drivers (nothing else), and the issue with slow boot when WB is on is still present.
So I went further and downloaded the Win10 ISO from the Microsoft website and did a fresh OS installation (nothing else), and the issue with slow boot when WB is on is still present.
I have no clue what is going on.
The laptop I'm using is Dell XPS 13 9310.

Is there a way to download an older version of WindowBlinds? Maybe that would help.
Thank you.