This is a continuation of topic
Packetbeat memory and cpu consumption when monitoring cassandra
I had the same problem. Packetbeat consumed a lot of memory. The problem was resolved by excluding AUTH_SUCCESS packets.
packetbeat.protocols.cassandra:
#Cassandra port for traffic monitoring.
ports: [9042]
ignored_ops: ["AUTH_SUCCESS"]
As I understood the packetbeat had been receiving too many of packets of this kind.