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
randomSettingsBuilder.put(SETTING_NUMBER_OF_SHARDS, numberOfShards()).put(SETTING_NUMBER_OF_REPLICAS, numberOfReplicas());
            
            
            SuppressCodecs annotation = getClass().getAnnotation(SuppressCodecs.class);
            if (annotation != null && annotation.value().length == 1 && "*".equals(annotation.value()[0])) {
                randomSettingsBuilder.put("index.codec", randomFrom(CodecService.DEFAULT_CODEC, CodecService.BEST_COMPRESSION_CODEC));
            } else {
                randomSettingsBuilder.put("index.codec", CodecService.LUCENE_DEFAULT_CODEC);
            }
            for (String setting : randomSettingsBuilder.keys()) {
                assertThat("non index. prefix setting set on index template, its a node setting...", setting, startsWith("index."));
            }
            
            randomSettingsBuilder.put(UnassignedInfo.INDEX_DELAYED_NODE_LEFT_TIMEOUT_SETTING.getKey(), 0);
            if (randomBoolean()) {
                randomSettingsBuilder.put(IndexModule.INDEX_QUERY_CACHE_ENABLED_SETTING.getKey(), randomBoolean());
            }
            PutIndexTemplateRequestBuilder putTemplate = indicesAdmin().preparePutTemplate("random_index_template")
                .setPatterns(Collections.singletonList("*"))
                .setOrder(0)
                .setSettings(randomSettingsBuilder);
            assertAcked(putTemplate.execute().actionGet());
        }
    }
    protected Settings.Builder setRandomIndexSettings(Random random, Settings.Builder builder) {
        setRandomIndexMergeSettings(random, builder);
        setRandomIndexTranslogSettings(random, builder);
        if (random.nextBoolean()) {
            builder.put(MergeSchedulerConfig.AUTO_THROTTLE_SETTING.getKey(), false);
        }