I don't know what a P100 is but I don't find a N99 more difficult to breathe than a N95 (but I do feel that I have to exert more force/pressure when breathing).
I use it to cycle and it's ignorable when cycling casually but discomfortable when going for performance. Anedoctally I don't find the extra effort to breathe to be a problem but just the saturated & hot air. So if I were to exhale each time with the mask of and inhale if it on it wouldn't be a problem. PS. I use masks w/ valves and those without one worsen this issue.
I use it to cycle and it's ignorable when cycling casually but discomfortable when going for performance. Anedoctally I don't find the extra effort to breathe to be a problem but just the saturated & hot air. So if I were to exhale each time with the mask of and inhale if it on it wouldn't be a problem. PS. I use masks w/ valves and those without one worsen this issue.