I’m an moderate-advanced user, and i often help my friends with malware and clean their systems, when i do that, i install Avast on their decent but low end systems, still more then capable to handle modern AV, core 2 duo + 2GB ram ect.
Now, when they are using Avast, they got cpu spikes, all 3 of them, including me! so this can’t be configuration/os related, no way!
To recrate the problem i reinstalled Avast on my pc, while my pc is very powerful, and total overkill, i5 @4.8Ghz constant frequency, and Samsung 840 pro SSD, i still mind this spikes which should not happen, at all.
It happens always, when you fast forward, pause-play, or even during normal playback, but at random times. I have no browser protection installed, neither they had. Very low junk installed very low number of addons, maximum performance tuned pc, with 8GB of ram as well.
This was exactly the same on version 7, and its still not fixed yet. Its same on fresh os/used, nothing changing.
Streaming 1080p video through flash is no joke even on a i5. The nature video you are sampling is probably one of the more taxing ones b/c of the the content. If you tried to download it, the 13 minute video is 470 megs. Like pictures not all frames are equal, some require more compressed bytes to render so that would explain the fluctuations. The fact that flash is involved aggravate the matter.
A lot better stability. I tried the video with flash and with html 5 player, with Avast enabled and disabled to see if Avast was contributing to the CPU fluctuations, but they were about the same.