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
try {
                context.suggest(source.suggest().build(searchExecutionContext));
            } catch (IOException e) {
                throw new SearchException(shardTarget, "failed to create SuggestionSearchContext", e);
            }
        }
        if (source.rescores() != null) {
            try {
                for (RescorerBuilder<?> rescore : source.rescores()) {
                    context.addRescore(rescore.buildContext(searchExecutionContext));
                }
            } catch (IOException e) {
                throw new SearchException(shardTarget, "failed to create RescoreSearchContext", e);
            }
        }
        if (source.explain() != null) {
            context.explain(source.explain());
        }
        if (source.fetchSource() != null) {
            context.fetchSourceContext(source.fetchSource());
        }
        if (source.docValueFields() != null) {
            FetchDocValuesContext docValuesContext = new FetchDocValuesContext(
                context.getSearchExecutionContext(),
                source.docValueFields()
            );
            context.docValuesContext(docValuesContext);
        }
        if (source.fetchFields() != null) {
            FetchFieldsContext fetchFieldsContext = new FetchFieldsContext(source.fetchFields());