Itanium suffered performance wise initially because they had trouble with compilers, but that's not the whole story. You also have to consider that AMD launched AMD64, which was backwards compatible, at about the same time. Later on the Itanium compilers got better, but on release it became a choice of "sluggish, incompatible and expensive Itanium with potential to perform well in the future" versus "backwards compatible, currently faster and cheaper x86_64." It didn't gain any real momentum to start because of this, which ultimately doomed it even when a lot of the issues were resolved later on.
> which ultimately doomed it even when a lot of the issues were resolved later on.
Was there ever a point in the Itanium's history where there were Itaniums that ran mainstream software with better performance than equivalently priced x64 processors?
As far as I know (which isn't very far, admittedly) they only really managed to reach parity with some performance gains over x86 in a few niches, but it's also a bit chicken-and-egg. It never had enough attention to really get the optimization and porting efforts it would have seen if it had been successful.
