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
throw e;
                }
            }
            if (logger.isDebugEnabled()) {
                if (lastKnownCount < numDocs) {
                    logger.debug("[{}] docs indexed. waiting for [{}]", lastKnownCount, numDocs);
                } else {
                    logger.debug("[{}] docs visible for search (needed [{}])", lastKnownCount, numDocs);
                }
            }
            assertThat(lastKnownCount, greaterThanOrEqualTo(numDocs));
        }, maxWaitTimeMs, TimeUnit.MILLISECONDS);
    }
    public static SearchRequestBuilder prepareSearch(String... indices) {
        return client().prepareSearch(indices);
    }
    /**
     * Retrieves the persistent tasks with the requested task name from the given cluster state.
     */
    public static List<PersistentTasksCustomMetadata.PersistentTask<?>> findTasks(ClusterState clusterState, String taskName) {
        return findTasks(clusterState, Set.of(taskName));
    }
    /**
     * Retrieves the persistent tasks with the requested task names from the given cluster state.
     */
    public static List<PersistentTasksCustomMetadata.PersistentTask<?>> findTasks(ClusterState clusterState, Set<String> taskNames) {
        PersistentTasksCustomMetadata tasks = clusterState.metadata().custom(PersistentTasksCustomMetadata.TYPE);
        if (tasks == null) {
            return List.of();
        }