Activate windows defender?

Avast Free Antivirus / Premium Security
1

I’d like to activate windows defender while Avast is disabled. Avast makes whole computer very slow, with hard disks always running at 100% and it’s unpleasant and unnecessary.

I had a nasty virus that Avast rooted out. I’d really like to keep Avast and not be forced to uninstall it. Is there a way to keep Avast, but so that it has no real time component that slows everything down? Can I use windows defender if Avast has to slow down my system?

i7 4770k, 16gb ddr3, samsung 840 evo 250, windows 7 64 system.

Thank you. I’m really glad that Avast is free and that it rooted out JS:Stopper. Nasty bit of malware that took deep scan of several hours and many deleted exe files to fix. I’d like to use Avast on demand- once a month, like I use malware bytes. No slowdowns, yes checkups.

2

It’s not a good idea to run windows defender and avast at the same time, because it causes interference and computer slow downs. When Avast is installed it will automatically disable Windows Defender.

You can even install Malwarebytes Antimalware (Free) to make sure your computer is clean of malware.

3

I would start with having one of the malware removal experts here check your system to see if really all the bad stuff is gone.
https://forum.avast.com/index.php?topic=194892.0

It is not a good idea to have Defender as your primary protection.
But if that is what you really want, you can set avast to passive mode.