So it seems all started with upgrade to 26.1 and at that time (January) issues with Neighbours Discovery. That was sorted out by the next upgrades/fixes but I started having similar issues with netflow/rrd. Once they are enabled, they cause high I/O and CPU demand. I tried, repair and reset netflow/rrd data plus manual removal of content of /various/netflow/ folder (with stopped neighbours discovery and netflow). Nothing helps; currently system is up to date: 26.1.6.
How to fix it?