FPS-Drops (5-10 FPS) not smooth

[vaxe]

Hello, I have a general question. I have the problem that I feel very strong FPS drops. I take Fortnite as an example.

If I have 150 FPS in Fortnite and suddenly "only" 120 then the whole thing feels very spongy. Is that normal? If I limit Fortnite from the beginning to 100 FPS, for example, the whole thing is smoother. Is it normal that I find FPS drops very unpleasant, even if it's only 5-10 FPS less?

Q
At the beginning in the plane I have 150 FPS, but then while flying over the map I suddenly have only for example 110 FPS. This 110 FPS then feels spongy again.

What I'm getting at is this:

I always see a lot of people running games with FPS drops. For example, Warzone livestreamers. They often have 150 FPS at times, then 120 FPS again, then 100 and on and on.... Why does this bother me so much and others somehow not? Is that normal?

I already had several monitors and also extra now a new PC and no matter what I do, it's always the same. Why can there be so many ignore?

My monitor:
ASUS TUF Gaming vg27aq (165 Hz & G-Sync).

Computer:
- GeForce RTX 3080 ASUS Strix OC V2
- AMD Ryzen 9 5900X
- ASUS ROG Strix X570-E Gaming
- G.Skill Trident Z NEO 32GB
- Corsair iCUE H150i RGB PRO XT AiO
- Lian Li PC-O11 Dynamic

My settings are as follows:

G-Sync enabled in NVCP
V-Sync enabled in NVCP

One last example. I can't play with shaders in Minecraft. I usually have 120 FPS or more, but the framerate fluctuates extremely around, which unfortunately makes the spearing experience really unbearable. Is this normal?

Thanks a lot, I really hope this is normal. Still, I find it strange that so many can ignore it so well.