PostgreSQL 10 now has an increasingly effective parallel query feature.
Response times from long running queries can be improved by the use of parallel processing. The concept is that we divide a large task up into multiple smaller pieces. We get the answer faster, but we use more resources to do that.
Very short queries won't get faster by using parallel query, so if you have lots of those you'll gain more by thinking about better indexing strategies. Parallel Query is aimed at making very large tasks faster, so it is useful for reporting and business intelligence queries.