Why is query duration is faster in the 2nd attempt than the initial attempt in Kibana dashboard?

Elastic Stack Kibana
1

Hi.

I recently realized that query performance is much better in the 2nd attempt than the initial attempt in Kibana dashboard .

Initial attempt.

Query Duration	5056ms
Request Duration	5257ms
Hits	1863206
Index	"openstack-*"

2nd attempt.

Query Duration	320ms
Request Duration	528ms
Hits	1863245
Index	"openstack-*"

Is there a cache in Query or Fetch phase that stays around for a while after the initial request?
My Kibana and elasticsearch version are both 5.1.1.

2

Because it caches it after the first time.

3

Is this cache the priority queue or something else?

4

No, it's https://www.elastic.co/guide/en/elasticsearch/reference/5.1/shard-request-cache.html#shard-request-cache

5

Totally understood . Thanks.