Thank You to Brett, Larry and Victor for your interesting info.
I found I missed to explain which kind of Everest ascent I am talking about; I am thinking about a full supported speed-record attempt, as Bruno Brunod already made (http://www.mounteverest.net/story/EverestspeedrecordattemptBetweenC1andC2Jun32005.shtml)
As You may be aware Bruno is one of the world best "Skyrunners" of the FSA
We are pretty well aware about tents, apparel and other 8000meters stuff You better consider.
On the other hand we found that, in order to really go fast, the most critical issue is actually the high weight of the double insulated boots : (possibly) the best one on the market, the OLYMPUS MONS EVO by Lasportiva, weight 2500 grams/pair. Unfortunately, given that boots are mobile masses, this is too much to go fast.
It may be useful to know that, in the latest 8000meters boots, the like as the Olympus, insulation comes from the low density PE inner boot. On the other hand most so called "pack-boots", designed to perform in the worst condition, sport several layers of sinthetic insulation the like as Thinsulate (up to 1600 !).
Does anyone has any experience, or ideas, on which kind of insulated boot we may want to consider, or about whick kind of better boot we may want to design ?
Thank You for your help