Is my CPU or Drive affecting my recorded gameplay

[bruised_lofi]

So a few days ago I tried using Shadowplay to record some Fortnite moments, and it was smooth sailing, but then, I noticed in my finished clip that there were lots of moments where the clip became extremely choppy or jittery

PC SPECS:

i5 7400

GTX1060 3gb

8GB RAM

And a single HDD I record to (Probably the issue)

Does recording to the same drive my OS and game located affect my recordings? I monitored my CPU and Disk usage in TM and Disk was on 80-90% basically all the time I was recording, should I not be retarded and buy myself a new drive to save my videos? SSD's have come a long way and I don't feel as scared if I do decide to continuously write files there, but is it worth it for a smoother recording or should I just buy a 1TB WD black?

 

I went on Fortnite and collected a bunch of dummy clips, then chucked in some music, watch the 1st minute and you can see the stuttering. Any help would be greatly appreciated

 

Link: (There was some audio desync, but I did this in a hurry so didn't have time to correct it)