Game does not run smoothly despite high FPS number?

I have the problem that my game does not feel fluent despite the high FPS count. In addition I have in the game Fortnite also often FPS break-ins on 40 FPS, which one notes straight in the play. Does anyone know why this could be and how to fix this? At first I did not have the problem with my PC but after about 2 years this problem arose. Many thanks in advance

CPU: Intel (r) Core (TM) i5-7500 3.40 Ghz

Graphics card: NVIDIA Geforce GTX 1060 6GB

16Gb ram

250 GB ssd and 1 tb hhd

Are your FPS permanently high? If so, how high?
And how do the FPS fluctuate? If they fluctuate greatly, it does not feel fluid.

Just try V-Sync.

A little more input would be helpful:

CPU temperature
CPU utilization
GPU temperature
GPU utilization
RAM utilization
Which memory (exactly, not only how big)

So I also have a 1060 and everything is super vllt is the GPU overheated or you have NEN 30fps monitor you do not know you can only munkeln

Is that only in online games like this?