One core is fully used when the window is minimized

[Dzhegash]

1. Build and run https://github.com/linebender/druid/blob/ff8ce2aacba3f34d5a165d4ae1dce253566e6814/druid/examples/blocking_function.rs
2. Press button "Start slow increment"
3. Minimize this window

This process full usage one of the cores when the window is minimized.

My env:
OS: Windows7
CPU: Intel Core i5
Rust(stable): rustc 1.56.1

[Dzhegash]

If remove widget Spinner, then everything is ok.

[cmyr]

Presumably this is a bug related to animations on windows.