WinUI 3 (Win32 and UWP) lags in resizing

[BreeceW]

Describe the bug UWP XAML windows fairly smoothly fit their content to the window as it is resized. WinUI 3 apps, both Win32 and UWP, do not. Win32 apps reveal a white background underneath, and UWP apps reveal the splash screen background color (yellow in the middle GIF below).

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Open a Win32 or UWP app that uses WinUI 3
2. Drag the edge of the window to resize it and observe a delay and undesirable colors as the content fits the window

Expected behavior There should be only unnoticeable delay in the content resizing to fit the window, like in UWP XAML.

Screenshots

UWP XAML (expected behavior)	WinUI 3 UWP (undesirable)	WinUI 3 Win32 (undesirable)

Version Info

NuGet package version: Microsoft.WinUI 3.0.0-preview1.200515.3

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
November 2019 Update (18363)	Yes
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Mobile
Xbox
Surface Hub
IoT