Supposedly, the well-manufactured low-flow toilets these days don't have so much of a problem. This is apparently due to active improvements, like using pressurized water, better modelling so that the suction works better, and, most simply, polishing (but not glazing, usually) the exit trap.

Of course, that doesn't help when the building's plumbing won't keep up without the greater water flow, as is often the case in older houses.