The two leading open source streamed search implementations are Elasticsearch Percolator, and Luwak. Both depend on the Lucene search engine. As the developers of Luwak, we have an interest in how its performance compares with Percolator. We therefore carried out some preliminary testing. Read more about the tests here:
http://www.flax.co.uk/blog/2015/07/27/a-performance-comparison-of-streamed-search-implementations/