Following @bob3160 advice I’m starting this new topic. I’ve been using Avast AV for years and now I had to uninstall it so that windows 10 is able to run properly, there were severe performance issues and apps were freezing/dragging. I noticed that if i disabled avast things did run normally, since it doesn’t make sense to have a disabled AV installed, I’ve unistalled avast and now I’m running windows defender =/
When you upgraded to 10 did you uninstall Avast and then install a fresh copy ?
That is what I did when I installed the initial windows 10 preview last year, and I have had zero problems with windows 10
I am on the insider programme fast ring so I get windows refreshes on approximately fortnight cycles
Currently on redstone version
I have used AIS throughout
No, this was a clean install of windows10 from dvd.
Was Avast a clean install or did you allow windows 10 to carry it over
At this point, I would suggest that you do a clean install of Avast:
https://goo.gl/4Ptzkf
There was nothing for windows to carry over since I’ve formated the drive, so yes it was a clean install of the OS and AV as well.
@bob3160 @essexboy guys as I said above it was a clean install 
What did you use to install windows 10 ???
Which version of Windows 10 is currently installed and what other security programs are running ???
@bob3160 I’ve installed 10 from dvd, version is 1511 (OS Build 10586.164). There were no other security programs runing only avast.
Go here >> https://forum.avast.com/index.php?topic=53253.0
Scroll down to second picture … Farbar Reccovery Scan Tool … run as instructed and attach the two diagnostic logs
See below the box you write in … Attachments and other options
Once posted, I’ll alert essexboy to take a look at the logs for possible problems.
Good morning. I’ve attached the log files.
Hmm run a comparison check with my windows 10 and I can see nothing untoward there that is not on mine apart from razer and nvidia although that should not make any difference
Although when I installed windows initially I did run the MS xbootmngr tool to optimise my drive and drivers. This cured a slow boot problem I was experiencing… From three minutes down to 30 seconds
I don’t recall having problems with boot times, I think a few seconds and I was ready to go (my ssd also helps a bit I think). The performance issues I’ve noticed was actually after login, during the normal use of the OS, for example firefox was really slow and non responsive at times specially when I’d press open a new tab, nvidia experience not working properly, non responsive, hanging, slow file explorer. After disabling avast the problems disapeared instantly and all running smoothly… I don’t understand.
There is probably something else that in conjunction with Avast slows the beast right down …
I would try an experiment and do clean install of Avast but select “Custom” and JUST SELECT the shields…no other options, including Virt/NG, etc.
See if you have same issue with just the basic shields ?
I also on every PC disable Hibernate…which also disables Fast Startup for W10…which uses Hibernate.
You still have SLEEP mode but Hibernate is a nasty beast that not only Windows but many 3rd party software guys (eg. Gfx Drivers, A/V, etc.) can have problems with.
It is just one simple command in CMD Prompt…you can always easily re-enable
http://www.tenforums.com/tutorials/2859-hibernate-enable-disable-windows-10-a.html
IMHO the above two items may shed light on the subject.
Hi @thekochs actually I always use custom installs/settings but I think I did choose shields + “secure virtual machines” (because it looked like a nice addition), so I’ll be trying that 
btw I also don’t use hibernate, sleep or fast startup already 
I’m a little sad about this but I have to say that avast + windows10 is a no go at the moment. Both desktop and a laptop show the exact symptoms and it’s not just me a friend of mine also says the same… so yeah good luck avast, hopefully you guys aknowledge these problems soon.
Follow instructions: https://www.avast.com/faq.php?article=AVKB33#artTitle
There is no incompatibility between Avast Free and Windows 10. You may have an individual computer hardware or software problem on the systems you describe that need to be sorted out.
The incompatibility isn’t between Windows 10 and Avast. In my house alone, I have 6 computers all running various versions of Windows 10. All protected by Avast free. Some computers are fairly new,
some of them are dinosaurs from Windows XP vintage. All are running without problems.
I suggest you follow Asyn’s suggestion and use the Support Tool to get to the bottom of your problems.