I would agree with Dan about not using the generic or genuine Compact/TriStar paper bags without the microfiltration layer. It seems that those bags clog with dust REAL QUICK, with hardly any dirt in the bag, & you have to change bags more than needed. The microfiltration bags are a bit better. In addition, you don't have to wash the cloth outer bag nearly as often, it doesn't get dirty & dusty as quickly if you use the microfiltration bags.
However, what I have found works even better is to use a Kenmore 5055 HEPA Cloth bag. Just take the cardboard collar off, & cut open the bag at the front seam that's closest to the collar. Stuff that into the outer bag, roll the rest of the bag over the rim, & put into the TriStar. Works much better, makes the TriStar maintain suction power much better. Tom Gasko has also said he uses the Numatic Henry HEPA Cloth bags too.
Rob
