qmlpreview slow to start up

For a medium sized desktop application with 4 different qrc file, referencing about 450 QML files in total, it takes about 10 minutes to launch the application built with Qt 5.15 (not ported to Qt 6 yet) with the QmlPreview qmljsdebugger option. All that time, the QtCreator executable takes up a significant amount of CPU.

Reducing the number of qrc files does improve the loading time (however the app cannot run of course). Analysis with procmon indicates shows that the files referenced in the qrc files (i.e. MyFile.qml) are being searched in a lot of locations in project's directory (i.e., "C:\Users\MyUser\MyProject\"), including odd ones like "C:\Users\MyUser\MyProject\MyApp\Users\MyUser\MyProjectMyApp\", "C:\Users\MyUser\MyProject\MyApp\MyUser\MyProjectMyApp\", "C:\Users\MyUser\MyProject\MyApp\MyProject\MyApp\", ... Also both "MyFile.qml" as "MyFile.ui.qml" are searched multiple times.

I've tried referencing the qrc files in the MyProject.pro file using absolute paths, however, that does not improve the loading time and the same locations are still being searched.

I have been unable to reproduce this with a separate project, because of the complexity of recreating the directory structures etc. One thing to note is that the qrc files are not all located in the projects directory:

• MyApp/qml.qrc (same directory)
• MyLibrary1/library1.qrc
• MyLibrary2/library2.qrc
• MyLibrary3/library3.qrc

Is this a performance issue with the qmlpreview side of QtCreator or am I perhaps misusing the qrc files because they are not all in the application's directory?