Question HDD activity strange?

[RightClickIntrest]

Let's make this quick.

I start up my computer and on boot up it's far slower than usual, I notice the HDD light is mostly off and barely flickers.
And because of this the whole computer is slow.

But then after some time the HDD starts acting like normal, activity light goes on and off like usual and everything is like it should be.

And then goes back to low activity :/

Any thoughts?

EDIT:

My specs are..
Intel (R) Core (TM) i5-9600k CPU @ 3.70GHz 3.70 GHz
16.0 GB of RAM
64bit operating system
*Windows 10 Pro

NVIDIA GeForce GTX 1050 Ti
and a Seagate BarraCuda 1TB Internal Hard Drive HDD ( 1.40 TB free )

After a bit of searching though I used the Local Disk properties tools to scan for errors.
Which the PC detected one and repaired it, after that the pc is now working properly but some slowness is still present time to time, with again the HDD picking back up and working like normally.

Also scanning again prompts no more errors.

 

[lvt]

What HDD do you have and how many space left does it have (especially Windows partition)?

 

[Ralston18]

Also update your post to include full system hardware specs and OS information.

 

[RightClickIntrest]

What HDD do you have and how many space left does it have (especially Windows partition)?

A Seagate BarraCuda 1TB Internal Hard Drive HDD with 1.40 TB free.

 

[lvt]

A Seagate BarraCuda 1TB Internal Hard Drive HDD with 1.40 TB free.

1.40TB free on a 1TB HDD?

 

[Sagittariusss]

I had an old HDD that performed just like that, even tho all sectors were still good, sometimes the disk is spinning at a lower speed than usual, so it still works but underperforms.