Lag when making lots of image occlusions

I’ve been facing a frustrating lag issue when using the native Image Occlusion feature in Anki. Specifically, any operation like creating new masks, editing existing ones, grouping/ungrouping, etc., becomes extremely slow and laggy. This happens as the number of masks increases.

However, when I open and review the same cards in AnkiDroid, there’s no lag at all — everything works smoothly.

Tried Image Occlusion enhanced , everything works smoothly.

Here are some relevant details:

Anki Version: 25.02.1 (Windows, Qt6)

OS: Windows 11
Tried Anki 25.02.1 on Linux Mint 22.1 same problem.

Hardware: Intel Core i3 (3rd Gen), 8GB RAM

Also tested on: Intel Core i5 (6th Gen), 16GB RAM – same issue

Tried downgrading to Qt5 version — did not help

Also tested Anki on Linux — same problem

Noticed during lag: QtWebEngineProcess.exe shows high CPU/memory usage

Currently, I'm using Windows Subsystem for Android (WSA) to run AnkiDroid natively on Windows 11, and it runs very smoothly. However, I would really like to return to using the Anki desktop version, as it offers more features and a better workflow for my needs.

Has anyone else experienced this issue with Image Occlusion? Any suggestions or workarounds to reduce the lag? I’ve searched around but haven’t found a solid solution yet.

Thanks in advance!

Start by reproducing Image Occlusion operations with increasing numbers of masks on the reported desktop environments, while monitoring QtWebEngineProcess CPU and memory usage. Compare creating, editing, grouping, and ungrouping masks with Image Occlusion Enhanced and AnkiDroid; done means the performance cause is identified and the desktop workflow no longer becomes progressively laggy.

Written by the indexing model from the issue text.