It may have been Avast Online security, an addon, which this morning showed up in Opera taskmanager with 50% CPU time under the flag of Opera.exe, also in Windows task manager, or Systemexplorer.
So I deleted it, to see if this may be the culprit?
Thanks for suggestions.

I have Avira browser safety installed.

I tried the developer mode but it's very unclear of what I should watch?
By the way, my system has 8GB memory and it more than fast enough for any browser or video.

It usually happens when Opera is left for a while idle.
But since there is no distinction between several Opera.exe operations running at the same time, I can't find out what the difference or purpose is, even with System Explorer. It all leads to the same process?
So if it jumps up again, I kill the most CPU consuming one, and another Opera session is still working OK.

I have found the task-manager, see what that will display?

Thanks so far for the help.

I have opted for developermode, but what should it display, or what to look at?
I noticed that Opera often when idle jumps into that CPU consuming mode of over 60%.
Killing that Opera.exe won't shut down the browser, so what is it, that's it's doing ?
I can't figure out what the difference is between Opera.exe and Opera.exe where one is the normal operation and the other a useless running one?

Well i'm using Opera 36.0.2130.65
But thank's for your reply.

I'm still struggling with Opera consuming over 50% CPU. Plus it's normal load which may in total run up to 80%.
I turned off the crashreporter, which was also causing high CPU while there was nothing to report, no crash.

It happens in idle mode, but also on the run.
It's not specified in Process explorer or taskmanager, only Opera.exe ?
I kill that high CPU process and Opera is still available, not shutting down.
So I wondered maybe an update check? Or whatever?
Can't get a hold on that mysterious Opera behaviour.
If browsing is significant slower, it's mainly caused by an open Opera, even if you are using another browser at that time.

Provider: opera-mini.net (turbo on)
IPadress: 141.0.xx.xxx
*Hostname: n24-06-04.opera-mini.net
*Socket: 35378

Turbo off:
*ForwardIP: 62.131.xxx.xx

With Opera Turbo on, my IP address becomes changed. 141.0.xx.xxx instead of 62.131.xxx.xxx
This caused trouble on some of my forums, due to anti-spam settings,
and blockades on country/location restrictions by NPO (Dutch television)
Turning Turbo off, the problem disappeared immediately.
It's very odd, since I usually use Opera almost any time.

Opera with NPO Dutch TV. Viewed in the Netherlands.

A series of Midsummer murders has been blocked by geographic location restrictions?
I'm Dutch and all other browsers play that movie without restrictions.

What could cause this problem?

Still waiting for an answer, just again 60% CPU time.
Stopped that process and Opera still working, so a totally unnecessary Opera process absorbs my CPU now and then.
There is no indication whatsoever of a virus or malware.

Overzicht Besturingssysteem:
OS Naam Microsoft Windows 7 Ultimate
OS Taal Nederlands (Nederland)
OS Kerneltype Multiprocessor Free (64-bit)
OS Versie 6.1.7601 (Win7 RTM)
OS Service Pack Service Pack 1
OS Installatiedatum 11-11-2012
OS Systeemfolder C:\Windows

Moederbord:
CPU Type DualCore Intel Core 2 Duo E8400, 3000 MHz (9 x 333)
Moederbordnaam ASRock G41MH/USB3 (2 PCI, 1 PCI-E x1, 1 PCI-E x16, 2 DDR3 DIMM, Audio, Video, Gigabit LAN)
Moederbord Chipset Intel Eaglelake G41
Systeemgeheugen 8160 MB
DIMM1: Kingston HyperX KHX1600C9D3/4GX 4 GB DDR3-1333 DDR3 SDRAM (8-8-8-22 @ 609 Mhz) (7-7-7-20 @ 533 Mhz) (6-6-6-17 @ 457 Mhz)
DIMM3: Kingston HyperX KHX1600C9D3/4GX 4 GB DDR3-1333 DDR3 SDRAM (8-8-8-22 @ 609 Mhz) (7-7-7-20 @ 533 Mhz) (6-6-6-17 @ 457 Mhz)
BIOS Type AMI (06/08/11)
Communicatiepoort Communicatiepoort (COM1)
Communicatiepoort ECP-printerpoort (LPT1)

Computer:
Computertype ACPI x64-based PC
Besturingssysteem Microsoft Windows 7 Ultimate
OS Service Pack Service Pack 1
Internet Explorer 9.11.9600.18124
DirectX DirectX 11.0

  Datum / Tijd                                      2016-02-16 / 09:49

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Video kaart Intel(R) G41 Express Chipset (3947052 KB)
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