Little FPS despite low workload?

I have had the problem for a long time that I have "low FPS" (~ 90-100FPS) in Fortnite when the workload is low.

Specifically: I have an AMD R5 2600 and an RTX 2060 and play on a 144hz monitor, but the load in this game is only around 50% load (measured with MSI Afterburner) and there's no heavy load on a single core at. The temperatures are also within reasonable limits and are around 75 ° but with a low fan speed. The problem does not occur with other games such as Battelfront 2.

With several videos on YT, the FPS that are achieved are almost twice as high.

Do you also have the settings on low?

Yes everything low except 3D res. Since 100%

Maybe exhibit this?!

Then the game is hardly playable and on YT everyone has the 3D resolution to 100%

They then have a better PC.