Do I need Win Defender if I use Avast Free AV?

The title says it all. I am actually using both without issue. Well, I do have one small issue and that is that WD pops up with a message at boot up that it has not been started. I think I can fix that by going into Services and have it start automatically with a delay. But do I really need both? I am using W7-64.

Brink said:

Hello Donny,

I would recommend to use both as well. However, you might install Microsoft Security Essentials. It will turn off Windows Defender and be used instead. I use this and Avast without any issues in Windows 7.

Hope this helps,
Shawn

I understand that having 2 AV is good in a way, if one misses second will catch etc.
And I believe that there may not be any issues between them (which is very good)

But isn't it a bit overkill?
I mean, probably both of them have on-access scanners (which is from detection point of view nice but It should double your time to access files as firstly it should be scanned by both of them)
It will be significant hit while using application which demand high resources or access lots of files.
For example gaming, It's already Hell to have one on-access scanner but two of them probably make your gaming experience terrible.

Or even for casual users: Internet surfing.
Every temporary file created/accessed by your browser will be scanned by one AV and then second one.

Or while putting one of them on full scan (of course in this case you can disable second one for some time)

But, it's just a theory.
And I am asking you (as a person who already uses this setup), do you experience any performance drawbacks or things like that?

Brink said:

Jav,

I have not seen any performance decrease at all on my system, but this will vary depending on your system. You may see a slight decrease in performance. If so, you can always just uninstall one of them.

Normally you would only want to have one antivirus program installed at a time to avoid them conflicting with each other, but both Avast and MSE have been designed to work together without a problem.

ok, thank you :)
But I am not using Avast as my main AV, so maybe for future reference.
Thank you anyway

gamepro127 said:

This is how Real-Time Scanning work

FILE F:\EXAMPLE.EXE WANTS TO TRANSFER TO C:\EXAMPLE.EXE
SCANNING EXAMPLE.EXE....
EXAMPLE.EXE: CLEAN!
EXAMPLE.EXE ALLOWED TO COPY TO C:\

Thats one antivirus/antispyware

Two:
SCANNING EXAMPLE.EXE....
EXAMPLE.EXE: CLEAN!
(2)
SCANNING EXAMPLE.EXE....
EXAMPLE.EXE: CLEAN!
EXAMPLE.EXE ALLOWED TO COPY TO C:\

You can see the slowdown...
Each file loaded into system memory, copied from one device or another or when another program tries to accesses the certain file, the antivirus must scan it first before allowing it to do so.
Now Two Antiviruses/antispyware...Well both programs must scan it first.

That's exactly what I meant!