Slower render with a Threadripper ?

I have to go deeper and analyse all the parameter.

But here is what I see, with the exact same project, and a CPU which seems to be used in the same way :

the render with my AMD Ryzen Threadripper 3960X (Desktop) is twice as much longer than with my Core i7-10750H (MSI laptop)...

On my desktop with threadripper, I work on an external drive, a Samsung T7, connected in USB-C, a lot of empty places on it...

The cash is on the same disk on both I think, it can be the problem maybe... Or something I don't know...

Any idea ? Tips ?