Laptop lags, cpu randomly spikes 100%

[ElebenZee]

So I just got a brand new laptop 4 days ago. I decided it would be wise if I set the battery option to power saver all the time to save battery, so obviously it slows the computer down. But then a while a go, my laptop hanged for some reason. I tried to force it to sleep by closing the lid. I waited a few seconds and opened the lid again, but to no avail, the system was still hanging, so I forced it to shut down by pressing the power button for about 5 seconds. It shut down and let it rest for a while. But when I opened the laptop again to do stuff, for some reason, the cpu spikes by 100% randomly even while doing normal stuff like browsing the web or watching videos at just 480p. I don't get why this happened considering my laptop was only a few days old. Furthermore, my laptop specs are core i7-7500u, 8gb of ddr4 ram and gt 940mx. Considering the specs, I'm very sure something like lagging even on normal usage is something so unusual. Any help or suggestion would be appreciated.

 

[velo3100]

Did you check which programs are running in the background while this happens?

 

[ElebenZee]

Did you check which programs are running in the background while this happens?

Thanks for answering, but I already found the solution. It turns out that my system has a malware which was detected by Windows Defender. The malware was hacktool:win32/kms which I got from a pirated copy of Microsoft Office 2016, probably its activator. Deleting it solved the problem, and my laptop regained its previous speed.