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
onFailure(e);
                                }
                            }
                        }
                    }, NO_TIMEOUT.equals(timeout) == false ? null : timeout);
                }
                @Override
                public void onFailure(Exception e) {
                    if (isDone.compareAndSet(false, true)) {
                        if (timeoutTask != null) {
                            timeoutTask.cancel();
                        }
                        listener.onFailure(e);
                    }
                }
                private void searchReady() {
                    if (isDone.compareAndSet(false, true)) {
                        if (timeoutTask != null) {
                            timeoutTask.cancel();
                        }
                        runAsync(executor, executable, listener);
                    }
                }
            });
        } catch (Exception e) {
            listener.onFailure(e);
        }
    }
    private IndexShard getShard(ShardSearchRequest request) {
        final ShardSearchContextId contextId = request.readerId();