Windows 7 is running very slow

[Kawaii Penguin]

So, I have an issue here.
I've done everything I can to check for any physical damage / errors, and I still can't figure out why this is happening.

My Windows 7 OS is running slow. when opening / tabbing into programs and using CPU-intensive programs... basically slow.

The memory itself (RAM) is not being capped out nor is broken. I have 2x4GB sticks.
I checked whether or not the memory is broken by running Windows Memory Diagnostics.
No errors.

The storage (1TB) is not capped out either. I still have 400 GB of storage space readily available.

I have a 6-core CPU installed (AMD FX6300) ~3.5GHz clock rate. No CPU cores are being overloaded.

The GPU's drivers are currently being updated, and I'm also running an AVG scan to check for viruses..

It's never been like this before.
Please help when you can.
Thank you.

P.S: If you want details on my system specs, here's a pastebin link of my dxdiag analysis.
http://pastebin.com/C380xTYe

(This is a 64-bit installation, by the way.)

[Part of overly-long title moved in to main text - - moderator]

 

[Tradesman1]

Also run a malware scan - MalwareBytes has a good free version. Check start up for any unneeded items that might be grabbing some memory.