My Whole PC is slower than usual lags, freezes, stutters and FPS drops. Is my GPU dying?

[Abdullahx9000]

So quite recently around a 1 month ago I noticed that my PC have been VERY slow. I am a YouTuber and thus need to record and edit videos. I am noticing a lot of lag in games such as Rainbow Six Siege, I usually play on Ultra settings with no lag and recording it, but now I am getting pixelation when looking at walls and everything.
In Sony Vegas I was able to edit videos no problem, but now my Preview Window lags a lot and looks pixelated and blurry and starts rendering really pixelated and bad quality videos. And everytime I click out of sony vegas to do something on my second monitor and then click back into Sony Vegas it freezes for around 5-10 seconds before letting me able to do anything.
Audio also seems to cut off from time to time while playing.

I REALLY don't know what is happening =[ Its frustrating me a lot as I haven't been able to upload any videos to YouTube for over a month

Here is my gear:
GPU: AMD R9 390 8GB
PSU: 750W Coolermaster
Processor: i7 6700
Ram: 16 GB

I might be missing some information, tell me if I do.

Any help is REALLY appreciated! And thanks in advance!

 

[Darkvillan]

Open your task manager and watch which programs are using the most memory / Disk / CPU / etc. You might have a virus on your computer using your card to mine bitcoin or some other crypto. Or you could just have a very demanding program in the background, this is the best way to check these things. If all of the usage seems normal to you, it could be a GPU or CPU issue that you are experiencing. Also if when you are clicking out of Sony Vegas, are you rendering? That would be a pretty good reason why it would stutter, as rendering is pretty demanding.

 

[Abdullahx9000]

Open your task manager and watch which programs are using the most memory / Disk / CPU / etc. You might have a virus on your computer using your card to mine bitcoin or some other crypto. Or you could just have a very demanding program in the background, this is the best way to check these things. If all of the usage seems normal to you, it could be a GPU or CPU issue that you are experiencing. Also if when you are clicking out of Sony Vegas, are you rendering? That would be a pretty good reason why it would stutter, as rendering is pretty demanding.

First of all thank you a lot for taking the time to answer! =]
As you can see in the screenshot below of the Task Manager, this is what my PC's usage rate usually.
https://imgur.com/a/ArcGW

When I click out of sony vegas I am not rendering, I am still editing the video. Sometimes I need to click out to drag something like a picture or sound files to add to my project and that causes it to freeze for 5-10 seconds. I really hope its not a GPU issue since the warranty stopped around 3 months ago. I hope the Task Manager screenshot is helpful