TrueRTA is surprisingly good with limited computer resources. I've used it on my wife's Celeron processor PC with good results using 1/24 octave resolution.

It moves decently and all. I didn't have too much trouble locating those frequencis when I was playing before. Do you use the averages? That helped some, but I was worried about missing something. Maybe I'm just expecting too much, like the bars in Winamp's little display.