This actual screenshot was made right before the latest upgrade, but I have another PC with the same Opera version and same OS (Win10-64bit) and much more load (3 windows with >1k tabs versus 1 window with ~300 tabs), where nothing alike has ever happened or at least I haven't ever noticed this.

In Opera Task Manager I can see that most CPU using tab continuously varies.
Also frequently, "Utility: Storage Service" uses most of CPU in Opera, but killing it doesn't help (CPU usage remains at 100%) and after a few seconds that service appears again.

Since then I have upgraded to the last Opera version, but nothing has changed.

Any ideas?

P.S. It seems like if allowed to wait without any user action for a long time (several minutes), the CPU usage gets back to normal, but just until I continue to work in browser again (like switching tabs & loading pages).

It seems that Opera is still displaying the animated background across all tabs (of which I have many opened) regardless of if the background is actually visible or not. As soon as I disabled the animated background (all backgrounds actually) the CPU and RAM dropped instantly down to 2-3% from the 30% I had it limited to. I got another small drop by disabling the matrix widget. And then realizing I never use the widget on the speed-dial screen I just disabled widgets entirely. My system is performing significantly better now that I've turned these functionally useless frills off.

I hope this helps others who are running into the same issue to resolve it. It may just be that you have some useless feature turned on that is running wild in the background when it shouldn't be.

On my PC system, an Intel based 8 core CPU running at around 4.5 GHz on turbo, with water cooler...
The CPU temp shown on Core-temp reaches 100 C. That is the max temp, this CPU is designed for. The CPU usage in proces explorer, is high and fluctuates... It can reach 30% which is very high.
Meanwhile using Google Chrome, the usage of both CPU and RAM is much lower... and the CPU temp is decreasing...

I moved away from Opera some month(s) ago because of performance issues with zero tabs and zero extensions active.

But what I noticed is that Opera hangs on history. I now had the time to do more investigation and for me the 105% CPU browser usage @Shift-Esc disappears when I rename my history file

@ C:\Users[Windows username]\AppData\Roaming\Opera Software\Opera Stable

I renamed the file "History" to "History" and my zero tab CPU 105% usage disappeared instantly. The only problem is that your history is gone as well ^^.

Might give Opera another try. Because Brave browser is also not the perfect alternative.

And yes, I know about GX, i use that one as well. But I still liked the old opera better when I could simply browse without my PC starting to make mild noise. And I would also rather not have to migrate everything once more.

I feel like this is one of those things when they make the platform worse without knowing it. But these things matter to folks. It's actually a big deal.

Opera used too much CPU and Harddisk in the Windows task manager.
This also together with the "System" Task.

I looked in the Opera Task-Manager and found that "Tab Speed Dial" is using too much CPU when pages are loading.
So in options i unchecked, disabled "Show Speed Dial Suggestions" and at once it runs much faster!

This must be an Opera error because this has nothing to do with opening new tabs with speed dials.

AND System Task is quiet now too
Perhaps this could be no coincidence and is also a Windows error.

I just upgraded to 32gb ram, and it starts using 14gb now.

Is this a problem? Unless Opera (or any other process) takes all free memory to itself and makes other apps work slower, IMO memory consumption is not a big problem. You have 18GB left for other tasks, after all

Same tabs open, nothing changed and no viruses.

Did anyone have this before? If so, how was it fixed?

Thanks in advance