niceness/priority:
ls /proc/$PID/task | xargs renice $PRIO

core affinity:
for p in `ls /proc/$PID/task`; do taskset -p -c $CORES $p; done

i/o // -c 0-3 (none, realtime, best-effort, idle) // -n 0-7 (0 is highest) // -p $PID
ionice -c 2 -n 0 -p $PID

FILE:
#!/bin/bash
PR1=`pidof PROGRAMM1`
PR2=`pgrep PROGRAMM2`
for p in `ls /proc/$PR1/task`; do taskset -p -c 1 $p; done
ls /proc/$PR1/task | xargs renice PRIO
for p in `ls /proc/$PR2/task`; do taskset -p -c 1 $p; done
for p in `ls /proc/$PR2/task`; do ionice -c 2 -n 0 -p $p; done
for p in `ls /proc/$PR2/task`; do ionice -p $p; done
ls /proc/$PR2/task | xargs renice PRIO