As suspected:
“creation” happens again and again, or at least the cmk process seems to think so and apparently does “whatever” to produce a significant amount of disk writes, therefore system load does not really decrease and remains at about 30 (usually is about ~1)
2021-05-10 13:30:15 [6] [main] dropping cached information about service “router104;Interface pfe-1/1/0.16383”
2021-05-10 13:30:15 [6] [main] [RRD helper 1548] created RRD for service “router104;Interface pfe-1/1/0.16383”, metric outqlen
2021-05-10 13:30:15 [6] [main] [RRD helper 1548] created RRD for service “router104;Interface pfe-1/1/0.16383”, metric outdisc
…
2021-05-10 13:30:51 [6] [main] reading metrics of service “router104;Interface pfe-1/1/0.16383” from “/opt/omd/sites/prod/var/check_mk/rrd/router104/Interface_pfe-1_1_0.16383.info”
2021-05-10 13:47:50 [6] [main] dropping cached information about service “router104;Interface pfe-1/1/0.16383”
2021-05-10 13:47:50 [6] [main] [RRD helper 1548] created RRD for service “router104;Interface pfe-1/1/0.16383”, metric outqlen
2021-05-10 13:47:50 [6] [main] [RRD helper 1548] created RRD for service “router104;Interface pfe-1/1/0.16383”, metric outdisc
…
OMD[rgi]:~$ ls -l /opt/omd/sites/prod/var/check_mk/rrd/router104/Interface_pfe-1_1_0.16383.*
-rw-rw---- 1 prod prod 169 May 10 13:47 /opt/omd/sites/rgi/var/check_mk/rrd/router104/Interface_pfe-1_1_0.16383.info
-rw-r--r-- 1 prod prod 5750760 May 10 13:47 /opt/omd/sites/rgi/var/check_mk/rrd/router104/Interface_pfe-1_1_0.16383.rrd