While it's not being seen by everyone, at all times, this seems to be more than just an isolated one-user issue. In addition the post I linked upthread from the disruptive ads thread, some others have been posted in the main 15 Nov thread such as:

https://www.flyertalk.com/forum/29178901-post1032.html

https://www.flyertalk.com/forum/29178954-post1034.html

https://www.flyertalk.com/forum/29178963-post1035.html

https://www.flyertalk.com/forum/29179225-post1036.html

For about a week after the 15 Nov changes, I had similar slowness and high CPU usage on one particular laptop, though I didn't investigate in detail at the time. It's been OK since then.