62 PCWorld FEBRUARY 2021REVIEWS TESTED: WINDOWS ON ARM
apps coded for X86
processors natively. Last
week, after an awkward
delay, Microsoft finally
published its long-
awaited 64-bit X86
emulator (go.pcworld.
com/x86m), allowing
Windows on ARM PCs
to run 64-bit X86 apps
via emulation. The vast
majority of apps today
are optimized for 64-bit
processors and the
larger amount of
memory they can
address. Because the apps are being
emulated and not running natively, they will
run more slowly than native code. Apple, too,
has shipped Macs running on its own 64-bit
ARM chip, the M1, and shipped a finalized
64-bit emulator alongside it.
Given the glowing reviews by our sister
site, Macworld, we know how well the new
MacBook Air (M1) (go.pcworld.com/m1ai)
and other M1-based hardware performed.
Now that Microsoft has shipped its own
64-bit emulator, we can more directly
compare how well Windows on ARM
compares to macOS on ARM.HOW WE TESTED
Our testbed was Microsoft’s Surface Pro X
(go.pcworld.com/mspx), running on afirst-generation SQ1 chip, a more powerful
version of Qualcomm’s Snapdragon 8cx. (We
did not have an SQ2-powered Surface Pro X
to test.) We downloaded and installed
Windows Insider Build 21277 and the
additional code, such as Adreno GPU drivers,
to allow 64-bit X86 apps to run. (Microsoft
warned that not every app would work, even
with its emulator.) We used Apple’s MacBook
Air (M1) as a comparison.
We already had a good idea of how slow
Microsoft’s Surface Pro X is—that was evident
from our original review (go.pcworld.com/
hslw). But these benchmarks provide insight
into just how slowly the Surface Pro X and its
SQ1 chip run with the new 64-bit X86
instruction emulator layered on top. We
hewed closely to the test suite fromApple and its M1-powered MacBook Air have accomplished what Microsoft
hasn’t: delivering a viable new ARM ecosystem of hardware and software.