Disadvantages

The above advantages are not free of cost. The disadvantages include:

• Increased memory usage.
  The workers threads allocate memory to store their intermediate results. When the worker threads finish, the supervisor allocates memory for the final result and collates the results for the workers. This collation results in a doubling of the memory requirements. Of course, after collation the supervisor releases the memory used by the workers.
• Slower execution on single CPU systems.
  Creating multiple threads, sending progress messages to the background manager, and collation of results for worker threads adds overhead compared to simply calculating the result directly in the foreground. On single CPU systems this results in slower processing compared to foreground processing. On dual-CPU and greater SMP systems, though, the advantage of using multiple CPU's in parallel exceeds the overhead of background processing.