Docker - LibreNMS load pages very slow

I’ve recently setup LibreNMS via Docker using this guide, which is based on this docker repository.
We run an external database.
The docker image runs on a VM, which on his turn runs on another VM (with Xen Hypervisor) (not sure if this gives any issues).

I got everything setup correctly and was able to add a host, but after succesful polling, it takes about 20 seconds to load the ports tab. The device is a Mikrotik router with only a few ports…

Validating the config:

What can I try?

Not a docker user for librenms, but for what you say I would check that librenms <-> database connection is not lagged.

Also, check resources on librenms docker/VM

Thanks for your quick reply.
I will for sure check the librenms database connection with my database administrator.
The VM has 2GB RAM and 5 CPU cores.

Btw, these are my librenms.env settings:

MEMORY_LIMIT=1024M
UPLOAD_MAX_SIZE=16M
OPCACHE_MEM_SIZE=128
REAL_IP_FROM=0.0.0.0/32
REAL_IP_HEADER=X-Forwarded-For
LOG_IP_VAR=http_x_forwarded_for

LIBRENMS_POLLER_THREADS=16
LIBRENMS_POLLER_INTERVAL=5

LIBRENMS_CRON_DISCOVERY_ENABLE=true
LIBRENMS_CRON_DAILY_ENABLE=true
LIBRENMS_CRON_ALERTS_ENABLE=true
LIBRENMS_CRON_BILLING_ENABLE=true
LIBRENMS_CRON_BILLING_CALCULATE_ENABLE=true
LIBRENMS_CRON_CHECK_SERVICES_ENABLE=true
LIBRENMS_CRON_POLLER_ENABLE=true

LIBRENMS_SNMP_COMMUNITY=librenmsdocker
MEMCACHED_HOST=memcached
MEMCACHED_PORT=11211
RRDCACHED_HOST=rrdcached
RRDCACHED_PORT=42217

That seems to be OK.

Meanwhile you wait your database admin, enter the librenms docker shell and check what process takes the more CPU.