Parallel Hint

 PARALLEL HINT

Parallel Hint instructs the optimizer to make use the given degree of parallelism in processing  the sql statement parallelly, instead of processing it serially.  

Parallel  execution can improve the performance of the query by dividing the work  among multiple processers or cpus,  Thus reducing the overall cost of Execution Plan. but you have to keep in mind that you MUST have enough CPU power available on the server, or else it can cause performance issues. 

Also Parallel execution can consume a significant amount of system resources, including CPU and memory.Therefore, it is important to monitor the system’s resources when using parallel execution and to adjust the degree of parallelism as necessary.

Refer https://expertoracle.com/2022/12/04/parallel-hint-in-oracle-database-ways-to-use-and-how-to-monitor/