@leocg
The opera://settings/system showed that hardware acceleration was turned off. I enabled it and, Voila! cpu went down to 2%.
Many thanks to the replies. I couldn't've done it alone.

@donq
Yes-that's what I experienced. A full screen Speed Dial with no borders and no way out of it.

@donq
Escape did not work. There was no min/max option visible to use.

Something very strange happened. Opera was running fine with about two dozen tabs opened. After a shutdown, I opened Opera and I only had the Speed dial and nothing else. No open tab bar. I couldn't access my task bar. There was no way to escape. I had to cntl/alt/delete to get the task manager and quit Opera. I did the same thing again and the same result, ie, use task manager to get out.
So I uninstalled Opera and then re-installed and now it's ok. I was on a fairly recent version of Opera.
What in the world just happened?

@leocg
The opera://settings/system showed that hardware acceleration was turned off. I enabled it and, Voila! cpu went down to 2%.
Many thanks to the replies. I couldn't've done it alone.

@pdw
Opera://gpu shows:
T560->
Graphics Feature Status
Canvas: Software only, hardware acceleration unavailable
Canvas out-of-process rasterization: Disabled
Compositing: Software only. Hardware acceleration disabled
Multiple Raster Threads: Enabled
Out-of-process Rasterization: Disabled
OpenGL: Disabled
Rasterization: Software only. Hardware acceleration disabled
Raw Draw: Disabled
Skia Renderer: Enabled
Video Decode: Software only. Hardware acceleration disabled
Vulkan: Disabled
WebGL: Software only, hardware acceleration unavailable
WebGL2: Software only, hardware acceleration unavailable
Problems Detected
Gpu compositing has been disabled, either via blocklist, about:flags or the command line. The browser will fall back to software compositing and hardware acceleration will be unavailable.
Disabled Features: gpu_compositing

 T460-> the only items disabled:

Canvas out-of-process rasterization: Disabled
Vulkan: Disabled

So what does this mean????

@burnout426
I forgot to add; for high cpu, you have to start the time roll, by clicking the slider bar(you may have to scroll down to see it, on the left).

@burnout426
Thank you both. That's just the kind of info I'm looking for. I'll try this stuff and get back to you.

@pdw I fprgot to add that both laptops are at the very latest Opera to date.

https://www.accuweather.com/en/us/brainerd/56401/weather-radar/333828

I disabled all my extensions prior to posting.
On my W8.1 Lenovo T560 laptop with 8GB ram and 256 GB SSD, this site goes into very high cpu, 70% to 90% as monitored by sysinternals/processexcp. The web page takes a long time to process the data, which is something I've always just had to wait until it got caught up. When the page is not being displayed, the cpu goes down to normal, around 1%.
But today I noticed quite by accident that my other laptop, Lenovo T460 on Windows 7 with similar hardware does not have the high cpu problem on the very same web site. Both of these laptops are brand new but I just prefer to run older windows OS's due to my older applications that I use.
It's very strange that the T460 has no problems at all with this site.
I run my laptops very tight as monitored by processexcp and very few non-system apps are running in background.
There's no way I can monitor extension cpu use, but as stated above, I have all extensions disabled for this posting.
I would really like to know what is the cause of the high cpu.
Anyone reading this, just click the link above and look at your cpu to see if it's overly high or just nothing at all. If you have the high cpu problem, maybe you can track it down to some hardware setting, or ???

@pdw What I mean is that the main window must be minimized in order to view any other window under it. This causes a problem, eg, when a site creates a sub-window. This sub-window is not visible and not obvious of its existence.
An example is why I had to call for support at a financial institution because it appeared a Java Script function was disabled, when in fact, the function had created a new window which was not visible to me. Only when I manually minimized the main window was I able to see the sub window that had been created.
Perhaps an option is required here to allow the main window to not be Always On Top.