From time to time I see websites that have been open in Orion for days, suddenly consuming a lot of CPU for whatever reason. In this case it is Renesas websites, I have 7 open and 3 of them randomly spike in CPU usage.
I have already seen this several times, which is why I use a CPU indicator in the menubar to prevent Orion from emptying my battery.
I can't provide steps to reproduce it. Here is a sample, not sure if it is of any help.
I'm posting this here as someone else might have seen similar things happening.
In this specific case, I refreshed one page after the other, and it turned out that all 3 high CPU tabs have been showing PDF files, so I guess that it might be related to PDF. However, I'm just a user, not a developer - so I'm just guessing here.