Even out here in the desert, where we have talcum powder dust, suction doesn't drop off until about 95% full, and even then the drop is modest. The 4 ply Aerus bags drop off at about 70%, and the enviro-care micro lined bags just slightly worse and both are very noticeable and performance degrades very quickly. I use the Perfect bags almost exclusively, but do use the other 2 to show the difference or for jobs that i don't want to leave in the bag. I don't feel bad throwing out a micro lined after one quick pass through a room since I can get those for about $0.25 vs. $2.00+ for the others.