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 value == null ? null : formatter.apply(value);
    }
    /**
     * Waits for all relocating shards to become active using the cluster health API.
     */
    public ClusterHealthStatus waitForRelocation() {
        return waitForRelocation(null);
    }
    /**
     * Waits for all relocating shards to become active and the cluster has reached the given health status
     * using the cluster health API.
     */
    public ClusterHealthStatus waitForRelocation(ClusterHealthStatus status) {
        ClusterHealthRequest request = new ClusterHealthRequest(new String[] {}).waitForNoRelocatingShards(true)
            .waitForEvents(Priority.LANGUID);
        if (status != null) {
            request.waitForStatus(status);
        }
        ClusterHealthResponse actionGet = clusterAdmin().health(request).actionGet();
        if (actionGet.isTimedOut()) {
            logger.info(
                "waitForRelocation timed out (status={}), cluster state:\n{}\n{}",
                status,
                clusterAdmin().prepareState().get().getState(),
                clusterAdmin().preparePendingClusterTasks().get()
            );
            assertThat("timed out waiting for relocation", actionGet.isTimedOut(), equalTo(false));
        }
        if (status != null) {
            assertThat(actionGet.getStatus(), equalTo(status));