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 builder;
    }
    private TestCluster buildWithPrivateContext(final Scope scope, final long seed) throws Exception {
        return RandomizedContext.current().runWithPrivateRandomness(seed, () -> buildTestCluster(scope, seed));
    }
    private TestCluster buildAndPutCluster(Scope currentClusterScope, long seed) throws Exception {
        final Class<?> clazz = this.getClass();
        TestCluster testCluster = clusters.remove(clazz); 
        clearClusters(); 
        switch (currentClusterScope) {
            case SUITE:
                if (testCluster == null) { 
                    testCluster = buildWithPrivateContext(currentClusterScope, seed);
                }
                break;
            case TEST:
                
                IOUtils.closeWhileHandlingException(testCluster);
                testCluster = buildTestCluster(currentClusterScope, seed);
                break;
        }
        clusters.put(clazz, testCluster);
        return testCluster;
    }
    private static void clearClusters() throws Exception {
        if (clusters.isEmpty() == false) {
            IOUtils.close(clusters.values());
            clusters.clear();
        }
        if (restClient != null) {