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
test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java
SmileXContent.smileXContent,
                        originalBytes
                    )
                ) {
                    loadedMetadata = Metadata.fromXContent(parser);
                }
                builder = SmileXContent.contentBuilder();
                builder.startObject();
                ChunkedToXContent.wrapAsToXContent(loadedMetadata).toXContent(builder, compareFormatParams);
                builder.endObject();
                final BytesReference parsedBytes = BytesReference.bytes(builder);
                assertNull(
                    "cluster state XContent serialization does not match, expected "
                        + XContentHelper.convertToMap(compareOriginalBytes, false, XContentType.SMILE)
                        + " but got "
                        + XContentHelper.convertToMap(parsedBytes, false, XContentType.SMILE),
                    differenceBetweenMapsIgnoringArrayOrder(
                        XContentHelper.convertToMap(compareOriginalBytes, false, XContentType.SMILE).v2(),
                        XContentHelper.convertToMap(parsedBytes, false, XContentType.SMILE).v2()
                    )
                );
            }
            for (IndexMetadata indexMetadata : metadata) {
                XContentBuilder builder = SmileXContent.contentBuilder();
                builder.startObject();
                indexMetadata.toXContent(builder, serializationFormatParams);
                builder.endObject();
                final BytesReference originalBytes = BytesReference.bytes(builder);
                XContentBuilder compareBuilder = SmileXContent.contentBuilder();
                compareBuilder.startObject();