Windows 10: All FullScreen Games, Get lag spikes on Pressing the alt Key

Hello, So i am having an issues here.
Every Game i play in fullscreen ,GTA V,Bf4 Dota 2,CSGO, Skyrim and all other game Lag on pressing Alt,
I go from 60fps to 45 each time i press it,
The thing is if i play in Windowed Borderless everything is fine, it was doing the same thing with my previous video card gtx 770 and now i have 980,but it's was not doing it on Windows 7, I use alt most of the time to speak online via Ventrilo or Teamspeak3,
Yes i try to change my teamspeak key to something else or try my game without any voip and i still get the lag,

it is weird and i really need to find why it does that.
any idea?

My setup is
CPU. FX 8350
MB, Sabertooth v2.0
Memory 16GB G.skill
GTX 980
PSU 750 TX
WIN 10 pro 64bit

:)

 

Windows Defender causes any and all graphical programs to stutter when either ALT key is pressed or released

I noticed something very strange a few weeks back. Whenever I would press or release either of my ALT keys, the game I was playing would exhibit a brief stutter. 100% reproducible, happens every time. To be clear, I don't mean that holding down alt
caused lag in game -- no, the mere act of pressing, or releasing either of the two alt keys would create a lag spike. Every single game on my computer exhibits this problem (Natural Selection 2, Factorio, Talos Principle, Overwatch, Doom... the list is diverse
enough to prove there's no common theme), in addition to... well any application that draws to the screen, it would seem. Even dragging the scrollbar of the Windows Start Menu's program list (while spamming alt alt alt alt) shows the problem.

Eventually I had the idea to open up task manager and see if anything stuck out -- it did! I noticed that if I pressed alt very quickly, MsMpEng.exe would immediately climb to the top of the list, and stay there for as long as I kept repeatedly pressing ALT.
(~6-8% CPU usage on my quad core. Top of the list, right behind System Idle Process).

If I turn off Real Time Protection in the windows defender settings, the problem completely vanishes. Turning it back on makes it reappear instantly.

 

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