High CPU usage when idle

I run Debezium Connect in a docker container and its average cpu usage is ~35% without any running application ie. with no activity.
Further apps in containers are Kafka, Zookeeper and PostgreSQL, all using ~1% on average.
In ctop no I/O can be seen.

Even if polling.interval.ms will be increased from 100 to 5000 no change in the performance can be observed.