i usually set the cpu speed to the lowest feasible frequency ... the slower the cpu, the cooler the computer, so less audible noise is produced by the cpu fan during the performance ... using gnome's cpufreq-applet, one can change the scaling governor/ frequency with two mouse clicks ...
so speaks the minimalist, cpu-wise..... ;-)
unfortunately, many netpd-synths and netpd-fx aren't that modest, cpu-wise.
well, using a more efficient signal processing engine, you can reduce the cpu load considerably :)
cheers, tim