Bitcoin daemon eats resources why?

Question

bitcoin

Good afternoon, I installed bitcoind on ubuntu 16, launched it, through top I see that bitciond uses 100-150% cpu
la at this time about 3, in the
server=1
daemon=1
config rpcuser=UNIQUE_RPC_USERNAME
rpcpassword=UNIQUE_RPC_PASSWORD
generation turned off, also started with with the -par=1
parameter, there are no errors in getinfo . What did I miss?
ps I searched in Google they write about some kind of "synchronization", someone waited 8 hours, someone 16, if I understood them correctly, of course.