The creation and termination of a process is relatively slow compared to the creation and termination of a thread, and is more costly in terms of system resources.
For example, sharing data and resources between processes requires shared memory and the mechanisms of interprocess communication; threads, on the other hand, have full access to the memory and other resources that belong to the process the threads are part of and can be coordinated using semaphores. For these reasons, thread-to-thread task context switches are faster than process-to-process context switches.
Because OS/2 can create and execute threads more quickly than processes, the preferred multitasking method for applications is to distribute tasks among threads in the same process instead of among processes.