I also saw lots of spiking on all 3-W10 browsers (Edge, Chrome, IE11) on the fox news site. I then checked cnn.com which is traditionally the highest activity video and photo media site page; it too spikes on all 3 browsers up to 99% CPU usage; up from 8% running idle. I suspect that the fox news site which appears to have 5-8 pages of photos, mixed text links, streaming media player insets, and lots of stuff appears to be very similar to cnn's page which traditionally was the browser benchmark for heavy content loading and loading time tests. I don't think it's too unusual, and I don't think it's just your computer.
Running all 3 browsers concurrently on the fox news site, my CPU usage goes from 11% - 99%.
Running all 3 browsers concurrently on the cnn.com site, my CPU usage goes from 16%-99%. It seemed to stabilize between 20%-70% when idle; as soon as I started scrolling in any of the 3 browsers, CPU usage jumped to 98%-99% and then dropped back to nominal levels.
Don't know if this helps, but it gives you a baseline on 2 other computers besides just yours (Henk's and mine).
Just a thought, but how much RAM do you have in the computer that gives you the spiked CPU usage? Mine is 8GB DDR3.
Best,
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