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
server/src/main/java/org/elasticsearch/search/SearchService.java
} else {
                listener.onPreQueryPhase(context);
            }
        }
        long success() {
            return afterQueryTime = System.nanoTime();
        }
        @Override
        public void close() {
            assert closed == false : "already closed - while technically ok double closing is a likely a bug in this case";
            if (closed == false) {
                closed = true;
                if (afterQueryTime != -1) {
                    if (fetch) {
                        listener.onFetchPhase(context, afterQueryTime - time);
                    } else {
                        listener.onQueryPhase(context, afterQueryTime - time);
                    }
                } else {
                    if (fetch) {
                        listener.onFailedFetchPhase(context);
                    } else {
                        listener.onFailedQueryPhase(context);
                    }
                }
            }
        }
    }
}