Elasticsearch High CPU when searching using Kibana

Hi All,

I am indexing 5000 Docs/sec.
I've a problem with search query that it consumes 100% of CPU when I do search with Kibana. its size 30 GB and have more that 1 Billion docs inside.
System Configuration: 16 GB RAM

Index Setting:

index.number_of_shards: 8
index.number_of_replicas: 1

I do some experiment with Segment also but i am still stuck.
Please suggest me i need to do something with Segment.

Sumit Gupta