The issue is HEPA filters are slow because they have to pass air through very fine filter. Then it get's clogged up and the performance plumments very quickly.<p>My guess is the solution is to get at least two filters. One that can quickly remove large amounts of dust from air without clogging up and one that can remove very fine particles.<p>I use a filter that does not have fine mesh but instead uses electrostatic force to attract particles. Does not need replacement -- it is metal box you just wash from time to time.<p>If I wanted really clean air I would then have another filter, HEPA. This would be able to do much better work since the other one moves large amounts of air quickly and removes particles before they would clog up HEPA filter.