It looks like Elasticsearch is currently missing support for concurrent searching and that this is a major prospective optimization to reduce latency.

Digression: this is not the topic at hand but I personally consider the fork OpenSearch to be an historical tragedy of duplication of work and a segregation of improvements. What would be even more anti-utilitarist would be to blindly *ignore* each other advances towards making better search.

Lucene concurrent search APIs are probably among the most important feature/optimization currently not leveraged by Elasticsearch.
The fork OpenSearch has a [pull request](https://github.com/opensearch-project/OpenSearch/pull/1500) implementing support for it.

See also the [corresponding issue](https://github.com/opensearch-project/OpenSearch/issues/1286) 

I believe it would be great for end users if you could take inspiration from the PR and work on this feature.

Great blog about the Lucene feature:
https://blog.mikemccandless.com/2019/10/concurrent-query-execution-in-apache.html?m=1
See also those performance results:
https://engineeringblog.yelp.com/2021/09/nrtsearch-yelps-fast-scalable-and-cost-effective-search-engine.html
test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java
return randomRepoPath(((InternalTestCluster) currentCluster).getDefaultSettings());
        }
        throw new UnsupportedOperationException("unsupported cluster type");
    }
    /**
     * Returns path to a random directory that can be used to create a temporary file system repo
     */
    public static Path randomRepoPath(Settings settings) {
        Environment environment = TestEnvironment.newEnvironment(settings);
        Path[] repoFiles = environment.repoFiles();
        assert repoFiles.length > 0;
        Path path;
        do {
            path = repoFiles[0].resolve(randomAlphaOfLength(10));
        } while (Files.exists(path));
        return path;
    }
    protected NumShards getNumShards(String index) {
        Metadata metadata = clusterAdmin().prepareState().get().getState().metadata();
        assertThat(metadata.hasIndex(index), equalTo(true));
        int numShards = Integer.valueOf(metadata.index(index).getSettings().get(SETTING_NUMBER_OF_SHARDS));
        int numReplicas = Integer.valueOf(metadata.index(index).getSettings().get(SETTING_NUMBER_OF_REPLICAS));
        return new NumShards(numShards, numReplicas);
    }
    /**
     * Asserts that all shards are allocated on nodes matching the given node pattern.
     */
    public Set<String> assertAllShardsOnNodes(String index, String... pattern) {
        Set<String> nodes = new HashSet<>();
        ClusterState clusterState = clusterAdmin().prepareState().execute().actionGet().getState();