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
Releasables.closeWhileHandlingException(searcherSupplier, readerContext);
                listener.onFailure(exc);
            }
        });
    }
    protected SearchContext createContext(
        ReaderContext readerContext,
        ShardSearchRequest request,
        SearchShardTask task,
        ResultsType resultsType,
        boolean includeAggregations
    ) throws IOException {
        checkCancelled(task);
        final DefaultSearchContext context = createSearchContext(readerContext, request, defaultSearchTimeout, resultsType);
        resultsType.addResultsObject(context);
        try {
            if (request.scroll() != null) {
                context.scrollContext().scroll = request.scroll();
            }
            parseSource(context, request.source(), includeAggregations);
            
            if (context.from() == -1) {
                context.from(DEFAULT_FROM);
            }
            if (context.size() == -1) {
                context.size(DEFAULT_SIZE);
            }
            context.setTask(task);
            context.preProcess();
        } catch (Exception e) {