Render svg preview images in File Explorer is too slow

### Microsoft PowerToys version

v0.100.2

### Installation method

GitHub

### Area(s) with issue?

File Explorer: Thumbnail preview

### Steps to reproduce

The first time i open the File Explorer in the directory where i have many svg images (50 at least). It renders the preview one by one in 4-5 seconds each. This process is too slow.

### ✔️ Expected Behavior

render more images in paralell?

### ❌ Actual Behavior

The first time i open the File Explorer in the directory where i have many svg images (50 at least). It renders the preview one by one in 4-5 seconds each. This process is too slow.

### Upload Bug Report ZIP-file

[example.png](https://github.com/user-attachments/assets/9fe61eaf-d060-4853-a088-151fcab4ccfd)

### Additional Information

Windows 11 25H2

### Other Software

_No response_

Start with the File Explorer thumbnail preview area and reproduce the issue using a directory containing at least 50 SVG images on Windows 11. Trace how SVG previews are generated and identify the relevant performance measurements before deciding on a change. Done means the previews render faster without regressions, verified with a comparable directory and existing project tests if available.

Written by the indexing model from the issue text.