You can make things more efficient if you make sure a BASIC program never waits on WAIT UNTIL.
WAIT UNTIL a=0 AND b=2 AND c=3 will keep the process runing in its slot.
UNTIL a=0 AND b=2 AND c=3 will put the process to sleep while wating and give up the time for another program to use. So other programs will go faster.
Sleep state is caused by WA(time), WAIT IDLE and WAIT LOADED. Any WAIT UNTIL will not put the process to sleep.