Have installed the latest 15.0.4 version for about a week now and performance / stability seems to have improved a little. Searched the forum again for tips and found a few:
1) disabled the clipboard history. (preferences - editor - clipboard)
2) Setting "None" for Light and Dark Style in configuration at:
user interface - appearance - Color Theme mode of version 15!
I like dark mode and use it for most of my tools
, but performance and stability are far more important to me.

I recently started thinking that maybe energy saving settings of the OS may cause the / some of the performance and stability issues. Anybody found any proof of this? Suggestions what settings to change?

What about the version of the Oracle client installed. Are there differences in stability between versions?

And I found a suggestion in this forum to start all over with the preferences by making note of your changes and then dropping the preference files and start all over...
Makes sense, because for a couple of years now I save my preference files and every time I get a new laptop I just copy those preference files over, changing some paths with find and replace when necessary.