SKP 2022 - resetting %appdata% (or just PrivatePreferences.json) allows models to load faster?

We have been troubleshooting this for many users since version 2018.
user1: Open large model file, 1 min to load full model (SKP set to 4X anti-aliasing)
user2 (same computer, different windows logon/profile) - same model file, - 20 seconds to load full model. (SKP set to 4X anti-aliasing)
Both users have no other plugins installed.

We reset PrivatePreferences.json (or all %appdqata% Sketchup folders) for user1 and the model loads for 20 seconds. (doing a ‘reset workspace’ does not fix this either).

User1 uses Sketchup for 2-3 days and is slow again until the PrivatePreferences.json is reset again.
What could they be doing wrong? or changing?
Window Layout?
Trimble Tech support has no idea it seems.
We opened a ticket 2 years ago and a tech assumed it may be open panels they keep open.

is this a bug?
Anyone seen this before?

The json file is readable text. Have a look and see what’s there before deleting it.

There is an issue where if the Materials tray is showing, and is selected to show In Model materials, loading can be slower. It’s possible that the user happened to choose that setting in the first couple of days, and deleting the preferences is hiding that tray.

Try getting user2 to do the same loading test while In Model materials are showing.

I also notice it’s slow when the Materials tray is loading a huge collection of materials as when I last saved with the Pantone collection (more than 1100 skm files) open.

The Outliner tray will also produce the same effect if it is open.