High CPU usage

Recently I've been experiencing consistently much higher CPU usage, often around 30-40% and frequently spiking much higher, including 100%.

I've read here that Windows Update is often the culprit. KB3020369 was already installed but KB3172605 wasn't. It now is but CPU usage is still high. There's no single process that appears responsible - quite a few take their turn, but AnVir Task Manager shows that Windows Update service in one of the svchost processes is certainly one of those regularly spiking.

Any help really appreciated.

I can only see 3 options.

Thanks a lot. I'll report back if there are any problems.

Right, done that but still problems. On startup after things had settled down and I hid various optional updates I didn't want, Windows Update process spikes around 15% CPU every 15 secs or so. After a while WU disappeared but was replaced by Windows Management Instrumentation process which behaves in an identical manner as WU, 15% CPU spikes every 15 secs. Again, any help really appreciated.

PS - I was reading in another thread, if I understood you correctly, you said installing KB3172605 would stop Trusted Installer process running because it replaces it with a more up to date process, but on startup Trusted Installer was still running here.

PS - I uninstalled Silverlight a while ago

Is there anyone else who can provide some assistance?