Large RPZ Zones with unbound recursor

Good day

We use Unbound in several Versions 1.17.1 and on older Servers 1.13.1-1 (Both are on Debian Servers)

Further we receive via IXFR some Spamhaus RPZ Zones. One of the RPZ file is about 137MB (aprox. 1.5Mio Records).

It seems, unbound gets slow to answer requests, especially when a IXFR occur.

This are our settings/tunings:

num-threads: 4

power of 2 close to num-threads

msg-cache-slabs: 4
rrset-cache-slabs: 4
infra-cache-slabs: 4
key-cache-slabs: 4

more cache memory, rrset=msg*2

rrset-cache-size: 512m
msg-cache-size: 256m

more outgoing connections

depends on number of cores: 1024/cores - 50

outgoing-range: 16384
num-queries-per-thread: 8192

Larger socket buffer. OS may need config.

so-rcvbuf: 32m
so-sndbuf: 32m

other cache sizes

key-cache-size: 16m
neg-cache-size: 4m

overwrite cache values (mb 20160802 Issue 17515)

cache-max-ttl: 3600

cache-min-ttl: 300

Is such a huge RPZ Zone file of for unbound?

did we missed something in our config?

If further Config are needed please let me know

Best regards

A