- Load VisualEditor (or 2017 Wikitext Editor) clicking on Edit button.
- Open a new tab in your browser to do something while editor is loading.
- After a while, go back to wiki tab where you’ve tried to load editor.
- Editor is not loaded: as soon as you switch tab, it stops loading.
I use Firefox 60.3.0esr on Debian. Seems to be the same with Chromium 61.
I don’t know if you can fix that or if it’s a browser issue.