I believe one needs the internal pressure to rise in order to help it boil faster. That's why pressure cookers can be dangerous and explosive if used wrong.
when there is high pressure, water actually doesn't boil faster (if the latter posts haven't already clarified for you)
there is a basic gas law pv=nrt
p=pressure, v=volume, n=# of molecules, r=constant #, T = temperature.
if temperature goes up, as it needs to for water to boil, one of two things must happen; pressure goes up, or volume goes up. so yes, high pressure actually does mean water boils faster.
have you ever heard of "making a cup of tea on top of a mountain" example?
on a high mountain, say everest; making tea is impossible; low atmospheric pressure allows water to boil at a low temperature so there's not enough heat to effectively brew tea from tealeaves.
the pressure cooker is dangerous since the volume of the water VAPOR builds as the temperature rises, and the pressure increases.
the whole purpose of this "pressure chamber pot" is not to "boil it faster", but so that the pressure of air above will force the water to have smaller volume; forcing flavor into the vegetables where there are less spice and flavoring, etc.