Help! My HA is running super slow

Since about one week, my HA instance is super slow and I can’t figure out what the reason might be. Maybe someone can support me to find the culprit?

My setup is a Raspberry Pi 4 with 4GB, passively cooled (~42°C) sipping <2 GB of RAM and with a CPU usage of <10%. I have disabled every single add-on already, problem stays. It’s not that only retrieving recorder data is slow, but even every HA menu. Since about two months, I’m running on a NVMe SSD via USB (with MariaDB), so I thought it might be that, installed a backup on a SD card, same problem. When using a clean installation (no backup) the problem goes away. This leads me to believe that it is an issue with my installation, not with my hardware.

I’m running out of ideas here. Help! Which logs could I check out?
An example for my HA core log is attached here:

P.S. Can I test my drives performance somehow? Read/write speed test?

I would start here: 2024.5+: Tracking down instability issues caused by integrations.