Purely amateur filmmaker since early days with Bolex standard 8mm camera. Travelled widely in oil industry shooting film for pleasure only.
My laptop has only an i3-350 CPU with an ATI HD5650 graphics card and I share your problem. In PD11 itself I find by juggling the Preview Quality/Display options I can usually get a reasonably smooth playback. Sometimes, counterintuitively, a higher quality setting plays back more smoothly! My last resort is to turn on non real-time preview. This usually gives me a smooth playback, with no sound and sometimes in slow motion, but these do not matter for colour correcting. I have not used ColorDirector a lot, but I use the same technic there with the addition on changing the picture size.
I wish we had the option to choose the codec and resolution of the proxy files but I have not found any way yet.
Good luck. John
Which version of PowerDirector are you using? I have been using PD11 for a while and using proxy files is completely transparent. They call them 'shadow files'. You can set Preferences to automatically generate them when using HD clips. If you don't it will ask you if you want to when you import the clips. Either way, a proxy file is generated, used in all editing, and then replaced automatically by the original when the final output is generated. I don't know what codec it uses or the parameters, I don't need to as it is all handled automatically.
Hope this helps.