Search queries are used for a lot of things in Platform Stack, and often you don't need to know the total count which causes an extra query to be performed which can be ommited.

On Solr / ElasticSearch this information comes "for free" as part of main search result so this is only relevant for database based search.

Discussion: http://share.ez.no/forums/ez-publish-5-platform/about-searchservice-and-count-queries
PR: https://github.com/ezsystems/ezpublish-kernel/pull/1153