> 
> I had been using linux for some years and then I switched to freebsd;
> I saw that freebsd just works faster than linux in many things. But now
> I'm trying NetBSD and I see that some things are slower than in NetBSD,
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

of course. others are slower ;)

> like the login for example. What's the ""problem"" ?

login is slow???
could you be more exact? logging in takes about a second or less on my
machine and little longer with old slow disk.