Long response time for logging events

Hello,

I just connected my heating pump to show me environment variables like outdoor-temperature, humidity, electric power consumption,…
However, when I look at the history of those sensors, it seems to take forever until a graph shows up. This although there are only data from the last two days inside the database.
Based on my feeling, this is consuming less time when I look on most KNX-based sensors.

My recordings are done using an external MySQL-database which is on my NAS-device.
Currently I already tried to set the recording commit_interval up to 120, as this was proposed somewhere.
Concerning the purge_keep-days I want to rise up from 10 days to approx. 120 days, as the database size shouldn’t matter too much when the database is externally, should it?
What else could I try to improve graph-performance?

Further I can’t get rid of sensors that have been in the configuration earlier and have been removed.

recorder:
   db_url: mysql://<user>:<pass>@<db-server-ip>/homeassistant_db?charset=utf8mb4
   commit_interval: 120
   purge_keep_days: 10