Why does FreeBSD take up 2GB of RAM after booting?

Question

FreeBSD

After installation and launch, after a while the system starts eating 2 gigabytes of memory out of 4, since I just started getting acquainted with BSD, please explain :)
here is what top:
last pid: 27591; load averages: 0.15, 0.20, 0.22 up 0+00:42:58 08:32:44
16 processes: 1 running, 15 sleeping
CPU: 0.0% user, 0.0% nice, 0.0% system, 0.3% interrupt, 99.7% idle
Mem: 7580K Active, 1131M Inact, 152M Wired, 90M Buf, 2213M Free
Swap: 513M Total, 513M Free

Answer 1

well, in this top you have 3.3 gigabytes free in fact

Answer 2

The fact that in the status of Inact (inactive) can also be considered free memory. Free+Inact=3343 MB is free in your case.