A process called Service Host: Local System is using up all of my laptops resources

Signed up so I could join this forum and present my problem too- I have too many 'service host' processes and the 'disk' section of my task manager is running at 90-100% which is not normal for my laptop. I usually run anywhere from 0-30%, sometimes up in 40%.

I had an obvious malware try to install a 'firefox update' on my laptop from a popup website unrelated to mozilla, which I simply closed. Next day when I turned my laptop on I manually closed a firefox update via task manager because I thought it was malware again, so I force closed it just in case, but it turned out to be the real firefox update and now my laptop is running a butt ton of 'service host' programs that are putting my task manager 'disk' in the red and at 90-100%.

As soon as I closed the update it said 'firefox cannot load XPCOM' and wouldn't start so I uninstalled and then reinstalled firefox and then rebooted, but my task manager 'disk' is still in the red. And now instead of listing one or two firefoxes in task manager, like normal, it's listing three. Dunno what to do but I don't want to close something I'm not supposed to again...

I've tried most of the solutions in this thread and none have worked, I assume because this is related to stopping firefox update somehow. I even went to mozilla firefox support forum where I had no luck when I followed the directions someone gave me there (uninstall and full clean reinstall firefox- which didn't work) I've uninstalled and reinstalled firefox several times but I still have all these service host processes.I also tried stopping windows defender and turning off the windows updates to never, tried stopping BITS, and turned off all startup processes.

I also used command prompt and entered 'sfc/scannow' and got this:

I don't know what to do. I've scanned using Advanced System Care 10 and IObit Malware Fighter, just in case there was a virus causing this or something, but no malware came up. The 'service host' processes only appeared after I stopped firefox update as it was downloading. They never appeared before. Thinking I might just wipe my laptop like new and put all my files on usb, but help would be greatly appreciated before I resort to that.

So i was playing GMod and it was lagging and so i check task manager and service host was taking a whole lot of cpu away (just cpu) so i changed windows update to never. but it was still taking so much cpu so i stopped the service and the cpu usage went WAY down :P

now i have that service temporarily disabled xD

Ian,

Thanks for the help. I don't like doing much digging down to solve problems, but i'm fed up with this one. In control panel there is no way to disable Windows update (outside of upgrading to professional), but this web site

https://www.cnet.com/uk/how-to/stop-windows-10-from-automatically-updating-your-pc/ 

Gives a partial solution that I'm going to run with for now.

Changing my "check for windows updates" to "never" worked! Now I just have to figure out why checking for updates was using up so much CPU. 

This problem has been annoying me for some months and having tried the different hints elsewhere on the thread and not wanting to change the Windows Updates to Never, I finally was motivated to do some detective work. Turns out, for me at least, the process “Service Host: Local System : Windows Update” is the culprit but I don't know why it does it.

In my case after rebooting PC all would be OK for a while but then, for no apparent reason, the CPU load would be high and fan would continuously run. So I tracked down the culprit with the following steps:

1. Reboot the PC.
2. Start Task Manager and select the Processes Tab.
3. Sort by CPU (normally you should only see Service Host: Local System intermittently at the top of the list as it consumes less than 1% CPU on my machine).
4. Locate the Service Host: Local System (sort on Process Name and go to the Windows Processes section).
5. Expand the Process to show all the sub processes.
6. Take a screen shot and save it somewhere to capture the processes (I dropped the screen shot into a Word Document)

Whenever I noticed that the CPU load was unusually high and the cooling fan running continuously I popped up Task Manager and repeated steps 1 to 6 above. Then compared the new screen shot against the reference screen shot under normal operating conditions.

Among the new processes listed were Multimedia Class Scheduler, Group Policy Client and Windows Update. Windows Update appealed to me as an easy target,  so I took a chance and stopped the process (right click on the process name and select Stop) and bingo the CPU load immediate falls back to normal.

I've repeated this procedure several times with no apparent side effects. I guess the Windows Update should start, check for updates, then stop again. But it is obviously not stopping correctly.

Obviously you need to be careful about stopping processes this way as it could render the system unstable. 

Hope this helps.

I have similar issue using Win 10 with AVG. Stopping AVG does not solve the problem. I've also run the scan to check Win 10 and that's fine - no problems found. I', pretty sure it service host itself. I can hardly bear to use my OPC anymore, I keep borrowing my wife's Win 7 oldie - which speeds along (also has AVG)

HELP