64-bit binaries net me a 15% performance increase with my application. Obviously it can vary per application, and depends on where the bottlenecks are. It's bee

64-bit binaries net me a 15% performance increase with my application. Obviously it can vary per application, and depends on where the bottlenecks are. It's been my experience that x86->amd64 is often beneficial: the x86 is so register starved that it makes up for the larger pointers, and most of the latter is mitigated through 32-bit relative instructions. Now PowerPC, sure. 32-bit PPC code does tend to run faster than 64-bit from my experience. The other advantage is being able to utilize more than 2GB of memory per process. The reason to favor pure 64-bit is to get rid of all that extra 32-bit compatibility code. WoW64, in this case, or ia32libs on Linux. Whether you're pragmatic about it or not, 32-bit will eventually go away. I'd prefer to see it sooner rather than for it to drag on for decades like IPv6. And yeah, WoW64 is a clusterfuck. Basically, Microsoft wanted to make porting 32-bit applications as easy as possible. Since some applications may have been hardcoded to System32, they stuck the 64-bit libraries there, and put the 32-bit ones in WoW64. They also cloned the registry so you actually have 32-bit and 64-bit keys (see KEY_WOW64_32KEY flag.) What can I say? Microsoft's always had a thing for rigid backward compatibility at the expense of common sense design. But they are still the market leader, so I guess they know a thing or two :/ I don't care for your Firefox example. What if one single tab needs >2GB, like say a really high-end WebGL game? What about other applications? People found similar tricks for getting more memory in 16-bit processes too (far pointers), but we aren't still using Win16. I'm accusing people of apathy because they resist change simply because it's change. I get being pragmatic, but at some point we have to cut ties with the past. Even Microsoft understands this, as you can no longer run 16-bit applications on the latest versions of Windows.