FTS is slow when the potential number of results is big, no matter that the sorts are on indexed fields

tried your recommendation and the results are similar. It takes 6.488936901092 for a query. This is getting the results without any offset.

This is how the index definition looks like:

{
  "type": "fulltext-index",
  "name": "image_fts-v2-test",
  "uuid": "6f906c8966cb3132",
  "sourceType": "gocbcore",
  "sourceName": "images_fts",
  "sourceUUID": "808e0bb49eb0ae702ced856f2824d649",
  "planParams": {
    "maxPartitionsPerPIndex": 342,
    "indexPartitions": 3
  },
  "params": {
    "doc_config": {
      "docid_prefix_delim": "",
      "docid_regexp": "",
      "mode": "type_field",
      "type_field": "m.t"
    },
    "mapping": {
      "analysis": {},
      "default_analyzer": "en",
      "default_datetime_parser": "dateTimeOptional",
      "default_field": "_all",
      "default_mapping": {
        "dynamic": true,
        "enabled": false
      },
      "default_type": "_default",
      "docvalues_dynamic": false,
      "index_dynamic": false,
      "store_dynamic": false,
      "type_field": "_type",
      "types": {
        "fts": {
          "dynamic": false,
          "enabled": true,
          "properties": {
            "cd": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "docvalues": true,
                  "index": true,
                  "name": "cd",
                  "type": "number"
                }
              ]
            },
            "dl": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "docvalues": true,
                  "index": true,
                  "name": "dl",
                  "type": "number"
                }
              ]
            },
            "ih": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "ih",
                  "type": "number"
                }
              ]
            },
            "ii": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "analyzer": "keyword",
                  "index": true,
                  "name": "ii",
                  "type": "text"
                }
              ]
            },
            "im": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "analyzer": "keyword",
                  "index": true,
                  "name": "im",
                  "type": "text"
                }
              ]
            },
            "iw": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "iw",
                  "type": "number"
                }
              ]
            },
            "mi": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "mi",
                  "type": "number"
                }
              ]
            },
            "mt": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "mt",
                  "store": true,
                  "type": "number"
                }
              ]
            },
            "np": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "analyzer": "en",
                  "include_term_vectors": true,
                  "index": true,
                  "name": "np",
                  "type": "text"
                }
              ]
            },
            "nv": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "docvalues": true,
                  "index": true,
                  "name": "nv",
                  "type": "number"
                }
              ]
            },
            "pi": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "pi",
                  "store": true,
                  "type": "boolean"
                }
              ]
            },
            "pp": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "analyzer": "en",
                  "include_term_vectors": true,
                  "index": true,
                  "name": "pp",
                  "type": "text"
                }
              ]
            },
            "pv": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "docvalues": true,
                  "index": true,
                  "name": "pv",
                  "type": "number"
                }
              ]
            },
            "s": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "s",
                  "type": "number"
                }
              ]
            },
            "st": {
              "dynamic": false,
              "enabled": true,
              "fields": [
                {
                  "index": true,
                  "name": "st",
                  "type": "boolean"
                }
              ]
            }
          }
        }
      }
    },
    "store": {
      "indexType": "scorch",
      "segmentVersion": 15
    }
  },
  "sourceParams": {}
}

This is how the index stats looks like:

As the servers load (3 servers) is very low (2%) would it make sense to make more index partitions? would this somehow make it work in parallel and faster? Now I have 3 partitions, would it work faster if I make 30 partitions?

I am doing something wrong?