Elasticsearch getting more memory and cpu Uses

Hi All,

I have ES Cluster size 20-30 GB(Total Number of Doc .50 billion document).I have four node 1 master node and 3 data node.I assigned 3 GB memory for ES.For Index Setting i am using 8 shards and 1 replica.I am running some query using Kibana.(like 30 query Every 20 Sec).I have 10-15 index and every index size is 1-2 GB.Some time i getting two much high cpu and memory usages and query response time is also getting stuck.

Please Verify I am putting right Configuration or do i need to change Something.

Sumit Gupta