WinUI 3 Performance: A Leap Forward · microsoft/microsoft-ui-xaml · Discussion #11096

Hello WinUI Community! Our mission is to make WinUI 3 the best native UI platform for Windows experiences and apps and performance is at the heart of that effort. Moving from WinUI 2 to WinUI 3 should always be a clear win for performance, and apps should get great results without heavy lifting. Why Now Pavan recently shared a blog post, in which "more fluid and responsive app interactions: Reducing interaction latency by moving core Windows experiences to the WinUI3 framework" was mentioned as part of our quality commitment. Making this a reality means delivering performance improvements at multiple levels, including within WinUI itself. This also reinforces our strategic commitment to WinUI as the native framework going forward. We know that performance is just one piece of the puzzle and that there are many other areas that deserve our continued attention. Rest assured, we remain focused on those as well. Where We're Focused We've been zeroing in on launch time, using File Explorer and Notepad as our primary benchmarks, with an emphasis on improvements that broadly benefit most apps. The Results So Far Here's what we're seeing for the WinUI portion of File Explorer launch:

Metric Improvement

Allocations 41% fewer

Transient allocations 63% fewer

Function calls 45% fewer

Time spent in WinUI code 25% reduction

When Can You Expect These Changes? These improvements will be brought out of the development branch soon, and you will see them showing up in the winui3/main branch. We'll also be bringing these changes into WinAppSDK 2.x where possible, though some changes may be too risky or complex to deliver as servicing updates. A Note on Breaking Changes Some optimizations involve small or large breaking changes and will require apps to opt in. For example, we're optimizing default control styles, which should work fine for most apps but could cause issues for apps that:

Expect to find a specific container element in a control template Rely on a property being set via an animation rather than a Setter

Each app can determine which of these changes to opt in to. Over time, perhaps as early as 3.0 or potentially in 4.0+, many of these will switch to opt-out, enabling the best possible performance by default.

Stay tuned for more updates, and thank you for being part of the WinUI community!

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