RAW image rendering lag persists even when enabling embedded thumbnail settings

Windows OS version

Windows 11

ImageGlass version

latest

ImageGlass release

Classic

1️⃣ Steps to reproduce

1. Go to ImageGlass performance settings/configuration.
2. Ensure UseEmbeddedThumbnailRawFormats is set to True (and set minimum dimensions to fallback values like 1920x1080).
3. Open a folder containing uncompressed camera RAW files.
4. Rapidly navigate through the images using the arrow keys or mouse wheel.

2️⃣ Actual behavior

There is a distinct, multi-second bottleneck/freeze or a prolonged "blurry mosaic" phase when advancing to the next file. System resources do not reflect active pre-loading of upcoming frames.

3️⃣ Expected behavior

The viewer should extract and paint the embedded preview image instantly, allowing for rapid culling/scrolling—matching the fluid performance seen in legacy C++ alternatives like FastStone Image Viewer or XnView MP.

4️⃣ Screenshots / Video / Sample image file

No response

5️⃣ Additional context

While the UseEmbeddedThumbnailRawFormats setting exists, the underlying framework pipeline or third-party decoding layers (such as Magick.NET) appear to add significant overhead before rendering the preview. A major optimization to bypass the full file pipeline for RAW file types during quick-browsing would vastly improve the app for hobbyist and professional photographers.

Start with ImageGlass's performance configuration handling for UseEmbeddedThumbnailRawFormats and trace the RAW image loading and rendering pipeline, including the third-party decoding layer mentioned in the report. Compare navigation behavior with embedded thumbnails enabled and define done as rapid RAW browsing that displays the embedded preview without the reported multi-second freeze or prolonged blurry phase.