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
if (runTestScopeLifecycle()) {
                clearClusters();
            } else {
                INSTANCE.printTestMessage("cleaning up after");
                INSTANCE.afterInternal(true);
                checkStaticState();
            }
        } finally {
            SUITE_SEED = null;
            currentCluster = null;
            INSTANCE = null;
        }
        awaitGlobalNettyThreadsFinish();
    }
    /**
     *  After the cluster is stopped, there are a few netty threads that can linger, so we make sure we don't leak any tasks on them.
     */
    static void awaitGlobalNettyThreadsFinish() throws Exception {
        
        
        assertBusy(() -> assertEquals(0, GlobalEventExecutor.INSTANCE.pendingTasks()));
        try {
            ThreadDeathWatcher.awaitInactivity(5, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
    private static void initializeSuiteScope() throws Exception {
        Class<?> targetClass = getTestClass();
        /**