Frame drops in games?

Hi

and I have the problem that I have frame drops from 100fps to 40fps for about 10 seconds and everything loads for so long and I know that it has to do with HDD and SSD, but I used to have these frame drops in not the games and now there's something else. And in fortnite you can display the net bug, and at 50% when I have the frame drops, there are yellow lines as shown in the picture.

Maybe a virus?
if so, with which free antivirus software could I scan my pc?

or can it be because I should clean my pc? I last did it 4 months ago.

Even the items in the inventory need something to be displayed and as I said 2 months ago I had it on HDD and it wasn't.

GTX 1050 ti

i5 7400

16GB RAM

"Maybe a virus?"

Rather unlikely.

Download HWMonitor and see how the temperature and clock of GPU and CPU behave. (Especially whether CPU or GPU throttles due to poor cooling)

Could possibly be a defective (and therefore slow) hard drive.