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
searchContext.searcher().setAggregatedDfs(readerContext.getAggregatedDfs(request.getAggregatedDfs()));
                searchContext.docIdsToLoad(request.docIds());
                try (
                    SearchOperationListenerExecutor executor = new SearchOperationListenerExecutor(searchContext, true, System.nanoTime())
                ) {
                    fetchPhase.execute(searchContext);
                    if (readerContext.singleSession()) {
                        freeReaderContext(request.contextId());
                    }
                    executor.success();
                }
                return searchContext.fetchResult();
            } catch (Exception e) {
                assert TransportActions.isShardNotAvailableException(e) == false : new AssertionError(e);
                
                throw e;
            }
        }, wrapFailureListener(listener, readerContext, markAsUsed));
    }
    protected void checkCancelled(SearchShardTask task) {
        
        try {
            task.ensureNotCancelled();
        } catch (TaskCancelledException e) {
            logger.trace("task cancelled [id: {}, action: {}]", task.getId(), task.getAction());
            throw e;
        }
    }
    private ReaderContext findReaderContext(ShardSearchContextId id, TransportRequest request) throws SearchContextMissingException {
        if (id.getSessionId().isEmpty()) {