- Edited
Almost got a sure reproducible scenario now:
1) open fresh profile, no extensions
2) open https://orionfeedback.org
3) cmd+T (new tab)
4) open https://youtube.com
5) click e.g. "Trending" to get some videos showing
6) scroll down a bit
7) cmd+1 back to orionfeedback.org
8) cmd+2 back to youtube.com (now unresponsive)
You might need to switch back and forth between the two taps more than once, but for me, the youtube tab becomes unresponsive within 1-2 tries, every time.
(on RC 0.99.127.1-rc)