How Windows on Arm Got Good: From Windows 10 to the 26H1/26H2 Split

Windows on Arm in 2017 was a curiosity that could barely run your apps. By 2026 it runs the overwhelming majority of them. That turnaround happened in a few decisive steps — here’s the timeline, and what each release actually changed.

2017–2018: the rough start (32-bit only)

Windows 10 on Arm launched on Qualcomm’s Snapdragon 835. It could emulate 32-bit x86 apps only — no 64-bit (x64) emulation at all. Since the software world was already moving to x64-only builds, this was a hard ceiling: a huge slice of apps simply wouldn’t install. The hardware was also slow. This era earned Windows on Arm its early bad reputation.

2020: x64 emulation appears (but only in preview)

In December 2020, Microsoft shipped a preview of x64 emulation in a Windows 10 Insider build. It was the breakthrough the platform needed — but it never reached a stable release on Windows 10. (You’ll see secondary sources claim “Windows 10 2004 added x64 emulation in May 2020” — that’s a myth; the real x64 milestone is this December 2020 preview, and it stayed preview-only.)

October 2021: Windows 11 — the real turning point

Windows 11’s launch is where Windows on Arm became genuinely usable. It brought, all at once:

• x64 emulation, generally available — finally, 64-bit Windows apps just run. Microsoft confirmed this is Windows 11-only; it never came to stable Windows 10 on Arm.
• Native Arm64 app support matured.
• ARM64EC — the hybrid ABI (announced mid-2021) that lets apps go native incrementally while keeping x64 plugins.

If you remember Windows on Arm being bad and haven’t looked since, this release is what you missed.

2024: Prism — the emulator gets fast

Windows 11 24H2 (the foundation of the first Copilot+ PCs) replaced the old emulator with Prism. Prism is meaningfully faster — Microsoft cited roughly 10–20% gains generally, and up to ~2× in some cases on Snapdragon X Elite. This is the update that made emulated apps feel close to native for everyday use.

2025: wider CPU-feature coverage

Through late 2024 into 2025, Windows updates taught Prism to expose more modern CPU instructions to emulated apps — AVX, AVX2, BMI, FMA, F16C — on by default for x64 apps. This unblocked a set of games and creative tools that check for these instructions. (Note: this arrived via a 2025 Prism update, not in base 24H2.) Windows 11 25H2 followed as a smaller enablement release on the same foundation.

February 2026: 26H1 — built for the next chips

Windows 11 26H1 shipped on February 10, 2026, built on a new platform foundation (“Bromine”). Unusually, it’s an Arm-only, chip-enablement release: no new end-user features, feature parity with 25H2 — its entire job is day-one support for next-generation Arm silicon. Snapdragon X2 is confirmed at launch. It isn’t offered as an upgrade you install; it ships pre-installed on new hardware.

October 2026: 26H2 ships — and a second Arm platform arrives

Windows 11 26H2 is the annual update for existing PCs on 24H2/25H2 — including older Snapdragon X Elite laptops — delivered as a small enablement package: a movable taskbar, a refreshed Start menu, File Explorer improvements and Task Manager NPU columns. Devices that shipped with 26H1 stay on their branch: 26H1 is built on a different Windows core, so it cannot upgrade in place to 26H2, and Microsoft says a path to a future release is coming.

The same month, NVIDIA RTX Spark reached pre-order: a Grace Arm CPU paired with a Blackwell RTX GPU and up to 128 GB of unified memory, running the same Windows on Arm stack. The first laptops ship October 16, 2026 — see RTX Spark and 26H1 vs 26H2.

The technical thread

Under the hood the story is three layers maturing: WOW64 + CHPE (the original x86-only path) → ARM64EC + Arm64X (Windows 11, enabling x64 and hybrid apps) → Prism (24H2’s fast modern emulator). One constant throughout: emulation is user-mode only — drivers always had to be native Arm64, which is still the rule today (see why some peripherals don’t work).

Where that leaves you

The takeaway: any opinion of Windows on Arm formed before late 2021 is out of date, and anything before 24H2 misses the performance jump. Today most apps run, a growing share are native Arm64, and the chip race (Snapdragon X2 + the new NVIDIA RTX Spark) is accelerating it further. Check whether your specific software runs in our database.