Massive Performance Issues with Database Update

[JustCodeIt4Head]

Hello,
I tried to set up PatrowlHears in a Virtual System and experience Massive Performance Issues when executing a DB Update via
sudo docker-compose exec patrowlhears bash -c 'cd backend_app && ./import_data_updates.sh'

When I execute the Command, the Update is starting and everything seems to work until the step "cve-run".
This step is going to around 15-20% and then the Progress is very slow, my VM is on a High Load (HTOP shows large amounts of RAM consumed by the Update) but nothing changes.
I notice too, that for some reason the RAM on my System seems to gets reduced from 12 GB down to 8, then 6, then 4 and then 2 GB. After stopping all Docker containers, free -m shows a total System Memory of said reduced size, however my VM Management Displays the original 12 GB still allocated without Balooing etc. After a VM Restart, the original amount of RAM is available again.

Is this a Bug with the Update Script? or what's happening?

My VM has 4 Cores allocated, 300 GBs of SCSI Storage and 12 GBs of Ram and the latest Updates for Debian 10 + Docker CE.
My Host Machine has 12 Cores, 32GB of RAM and 4 TB of Storage and i have nothing running that needs too much ressources.