I doubt that it would do anything, as you're looking for a specific temperature in mashing. You can speed up mashing by testing for conversion at say....25 minutes instead of an hour. If you have it then you can continue with the process.
As for boiling under pressures other than atmospheric, I've actually done some looking into this. Here is a link to an abstract of a paper that's relevant (you might be able to access the full text through a university like I can): http://pubs.acs.org/doi/abs/10.1021/jf0481296
The meat of what you want to know is this (quoted from the article):
The results obtained indicate that the rate of isomerization roughly doubled for every 10 °C increase in temperature (average change was 229% per 10 °C increase). Isomerization of cohumulone to isocohumulone proceeded at a rate equivalent to that of humulone and adhumulone. High temperatures quickly led to degradation products, as evidenced in the dramatic decrease of iso-alpha acid concentration beyond 18 min of heating at 130 °C. While the rate of isomerization slowed at temperatures below 100 °C, substantial amounts of iso-alpha acids were still produced at 90 °C. This is significant if hot wort is held at temperatures just below boiling after the kettle boil is completed, while in the whirlpool, or awaiting transfer to a heat exchanger.