In Java Streams, parallelism is achieved by using the Fork-Join principle. Using parallel Streams is easy and no expertise is needed for thread handling. Designing and writing multi-threaded applications is challenging and error-prone, hence Streams has two implementations: sequential and parallel. Parallelism utilizes hardware capabilities at their best, as nowadays, more CPU cores are available on a computer, so it doesn't make sense to have a single thread in a multi-core system. Let us look at these factors which are meant for Streams' performance. In Java8 Streams, performance is achieved by parallelism, laziness, and using short-circuit operations, but there is a downside as well, and we need to be very cautious while choosing Streams, as it may degrade the performance of your application. In the last few years, the programming has been changed drastically per the way hardware evolved, where parallel processing, real-time, cloud, and several other approaches have been introduced to achieve higher performance.

Java8 Streams was a very big addition to the Java programming language which was introduced to achieve the best performance.

Java parallel streams