Elasticsearch: Force merge reduced performance

I forced merged my index to reduce segment size from 82 to 5, with the hope of increasing the search performance.

Dashboard load time for the same index was as follows,

82 segments - 10 seconds

5 segments - 250 seconds

As per the documents referred performance should be increased, any idea for this behavior?

My Data information

1 index only

5 shards

50 million docs

Index size (primary)

  • 2 GB - after force merge

  • 3.5GB - before force merge

Replicas - 1

My cluster information,

Es, kibana - 6.3.0 version

3 node cluster

15gb 4 core

7gb heap

400Gb disk per node