The PERFORMANCE statement controls the number of threads that are used in the optimization phase. You can also specify that multithreading not be used in the optimization phase by using the NOTHREADS option.
You can specify only one PERFORMANCE statement. The PERFORMANCE statement supports the following performance-options:
If you use both the NTHREADS= and NOTHREADS options, then the NTHREADS= option is ignored. If you use a PERFORMANCE statement, then it overrides any global threading settings that might have been set using the CPUCOUNT=, THREADS, or NOTHREADS system option.