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
.setIgnoreIdleThreads(false)
                    .execute(listeners.acquire(hotThreadsRef::set));
            }
            try {
                detailsFuture.get(60, TimeUnit.SECONDS);
            } catch (Exception e) {
                logger.error("failed to get full debug details within 60s timeout", e);
            }
            logger.info(
                "{} timed out\nallocation explain:\n{}\ncluster state:\n{}\npending tasks:\n{}\nhot threads:\n{}\n",
                method,
                safeFormat(allocationExplainRef.get(), r -> Strings.toString(r.getExplanation(), true, true)),
                safeFormat(clusterStateRef.get(), r -> r.getState().toString()),
                safeFormat(pendingTasksRef.get(), r -> Strings.toString(r, true, true)),
                safeFormat(
                    hotThreadsRef.get(),
                    r -> r.getNodes().stream().map(NodeHotThreads::getHotThreads).collect(Collectors.joining("\n"))
                )
            );
            fail("timed out waiting for " + color + " state");
        }
        assertThat(
            "Expected at least " + clusterHealthStatus + " but got " + clusterHealthResponse.getStatus(),
            clusterHealthResponse.getStatus().value(),
            lessThanOrEqualTo(clusterHealthStatus.value())
        );
        logger.debug("indices {} are {}", indices.length == 0 ? "[_all]" : indices, color);
        return clusterHealthResponse.getStatus();
    }
    private static <T> String safeFormat(@Nullable T value, Function<T, String> formatter) {