Re: His reason for why people don't use PAE is rather amusing. It couldn't be because PAE is a pain the rear for programmers, could it?
That and performance drops of 30% to 90%. As you pointed out, it's a real headache for programmers, since it's basically a RAM disk, and tracking >32bit addresses and values across the margin between segments when all you've got to do it with are 32bit regisiters is difficult and saps performance. When large footprint programs use PAE to access more than 2 or 3gig of RAM (note that the non-PAE limit is 2gig per process in most configurations) many operations requires several steps to accomplish work that would otherwise be done by a single instruction.
PAE is a rather ugly and inefficient kludge, and is why Intel has created Itanium for workstations and servers instead of continuing to develop Xeon. In some ways, PAE takes the 386 architecture back to the days of the "brain dead" 286.
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