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
protected static final int DEFAULT_MAX_NUM_SHARDS = 10;
    /**
     * The current cluster depending on the configured {@link Scope}.
     * By default if no {@link ClusterScope} is configured this will hold a reference to the suite cluster.
     */
    private static TestCluster currentCluster;
    private static RestClient restClient = null;
    private static final Map<Class<?>, TestCluster> clusters = new IdentityHashMap<>();
    private static ESIntegTestCase INSTANCE = null; 
    private static Long SUITE_SEED = null;
    @BeforeClass
    public static void beforeClass() throws Exception {
        SUITE_SEED = randomLong();
        initializeSuiteScope();
    }
    @Override
    protected final boolean enableWarningsCheck() {
        
        
        return false;
    }
    protected final void beforeInternal() throws Exception {
        final Scope currentClusterScope = getCurrentClusterScope();
        Callable<Void> setup = () -> {
            cluster().beforeTest(random());
            cluster().wipe(excludeTemplates());
            randomIndexTemplate();
            return null;
        };
        switch (currentClusterScope) {