Windows 11 is getting support for one of the most interesting x86 architecture extensions in recent years: APX, short for Advanced Performance Extensions, Intel's extension to the 64-bit instruction set. Insider build 29695.1001 in the Experimental channel includes a settings switch that lets Windows use APX, with the description "Let Windows use APX for better performance". Turning it on requires a restart.
Intel introduced APX in July 2023. It doubles the number of general-purpose registers available to the processor, from 16 to 32. More registers mean fewer memory accesses, which are among the slowest operations for a CPU. Intel also describes more efficient instructions and the ability to avoid some hard-to-predict branches, the points where the processor must guess which path a program will take: when it guesses wrong, it loses time recovering. According to figures Intel presented, code compiled with APX has 10% fewer loads and more than 20% fewer stores than the same code compiled for the Intel 64 baseline, and about 10% fewer instructions. Those numbers come from a prototype and may change in the final version.
Don't expect Windows to become 10% or 20% faster, though. Microsoft has not yet published benchmarks for the switch, and the gain depends on two conditions. The first is hardware: APX requires a supporting processor, and according to Windows Latest Intel Nova Lake will be the reference family for consumer PCs, while current CPUs cannot use it. The second is software: applications must be recompiled with APX support, and Intel says source code changes are generally not expected. The GCC 15 compiler already includes the full APX instruction set.
The point matters for the market too. Owners of current Windows 11 PCs won't be able to use the feature, and it could become a reason to buy new computers just as Windows 10 approaches the end of extended support in 2027. Intel has also confirmed that AMD will support the extension.
The rollout timeline is not yet known. Microsoft has not said when the feature will reach stable Windows 11 releases, and Nova Lake, Intel's next desktop processors, are expected in 2027.
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