root@srv01:~# nano /etc/unbound/unbound.conf
server:
# use all CPUs
num-threads: <number of cores>

msg-cache-slabs: <2^num-threads>
rrset-cache-slabs: <2^num-threads>
infra-cache-slabs: <2^num-threads>
key-cache-slabs: <2^num-threads>

# more cache memory, rrset=msg*2
rrset-cache-size: 100m
msg-cache-size: 50m

# more outgoing connections
# depends on number of cores: 1024/cores - 50
outgoing-range: 950

# larger socket buffer
so-rcvbuf: 4m
so-sndbuf: 4m