Slow response time even though slow logs show fast (query+fetch)

[Abhishek_Singh2 (Abhishek Singh)]

I am having trouble with my Elasticsearch nodes/queries ……. I have 3 physical nodes in which all 3 are master + data nodes. I am running a simple filter query in slow logs I see query +fetch time as 8 millisec sometimes 17 millisec but response time on kibana is 300 to 500 millisec.
My index size is < 1 GB with 1 shard 2 replica, and the cluster has 16*3 GB RAM. Data size returned after filter query is around 1Mb(without whitespace).
Here is my slow logs

[2022-03-25T22:59:42,446][TRACE][index.search.slowlog.fetch] [debbf06e052fb476f254ba1234123] [khoj_prod_001][0] took[17.7ms], took_millis[17], total_hits[196 hits], types[_doc], stats, search_type[QUERY_THEN_FETCH], total_shards[1],

source[{
    "size": 300,
    "query": {
        "bool": {
            "filter": [
                {
                    "term": {
                        "hub_id": {
                            "value": 1,
                            "boost": 1
                        }
                    }
                },
                {
                    "term": {
                        "category_id": {
                            "value": 3,
                            "boost": 1
                        }
                    }
                },
                {
                    "nested": {
                        "query": {
                            "bool": {
                                "filter": [
                                    {
                                        "term": {
                                            "kml_wise_slot.kml_id": {
                                                "value": "610fe6b10dab1241283de493",
                                                "boost": 1
                                            }
                                        }
                                    }
                                ],
                                "adjust_pure_negative": true,
                                "boost": 1
                            }
                        },
                        "path": "kml_wise_slot",
                        "ignore_unmapped": false,
                        "score_mode": "none",
                        "boost": 1
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1
        }
    },
    "sort": [
        {
            "scores.value": {
                "order": "desc",
                "nested": {
                    "path": "scores",
                    "filter": {
                        "term": {
                            "scores.key": {
                                "value": "ranking_scores",
                                "boost": 1
                            }
                        }
                    }
                }
            }
        }
    ]
}], id[],