Large drop in performance when using font features

### Windows Terminal version

1.22.2362.0

### Windows build number

10.0.19045.4894

### Other Software

[Iosevka Term 31.6.1](https://github.com/be5invis/Iosevka/blob/v31.6.1/doc/PACKAGE-LIST.md)

### Steps to reproduce

1. Download and install [Iosevka Term 31.6.1](https://github.com/be5invis/Iosevka/blob/v31.6.1/doc/PACKAGE-LIST.md).
2. Set font face to Iosevka Term
3. Set any of the available font features to an arbitrary value.

### Expected Behavior

Smooth scrolling/selection.

### Actual Behavior

Selection via mouse and scrolling becomes very sluggish. It is less noticeable on a blank cmd, but it gets worse and worse with more colors, characters and a bigger window. Especially noticeable when using a command line editor like Vim/Helix via WSL.

Removing the font features immediately makes everything smooth again. I can't reproduce this behavior with Cascadia Code, only noticed it with Iosevka Term so far.

Reproduce the issue on Windows Terminal 1.22.2362.0 with Iosevka Term, font features enabled, and a large colored terminal window; compare behavior with features removed and with Cascadia Code. Trace the terminal's font-feature and rendering path, then verify that scrolling and mouse selection remain smooth under the reported workloads.

Written by the indexing model from the issue text.