Thank you.
It's already installed and I think that my config is ok, when I said old pc it's just my old one, not a prehistoric pc :)
Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz
16Gb ram and freenas installed on a 500Gb ssd.
But like I taught, I have some prob....I posted in french on international part of the forum but till now no answer.