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
/*
                 * The query on the search context right now doesn't include
                 * the filter for nested documents or slicing so we have to
                 * delay reading it until the aggs ask for it.
                 */
                () -> context.rewrittenQuery() == null ? new MatchAllDocsQuery() : context.rewrittenQuery(),
                context.getProfilers() == null ? null : context.getProfilers().getAggregationProfiler(),
                multiBucketConsumerService.getLimit(),
                () -> new SubSearchContext(context).parsedQuery(context.parsedQuery()).fetchFieldsContext(context.fetchFieldsContext()),
                context.bitsetFilterCache(),
                context.indexShard().shardId().hashCode(),
                context::getRelativeTimeInMillis,
                context::isCancelled,
                context::buildFilteredQuery,
                enableRewriteAggsToFilterByFilter,
                source.aggregations().isInSortOrderExecutionRequired()
            );
            context.addQuerySearchResultReleasable(aggContext);
            try {
                final AggregatorFactories factories = source.aggregations().build(aggContext, null);
                final Supplier<AggregationReduceContext.Builder> supplier = () -> aggReduceContextBuilder(
                    context::isCancelled,
                    source.aggregations()
                );
                context.aggregations(new SearchContextAggregations(factories, supplier));
            } catch (IOException e) {
                throw new AggregationInitializationException("Failed to create aggregators", e);
            }
        }
        if (source.suggest() != null) {