Why is Fortnite sometimes so ineffective?

Hello Gamer Community I have a question I'm a Fortnite player and play on the pc. I'm really good there too, I would say so on the level of the pros but on some days the game feels so leggy and then I can't use all of my skills. The internet doesn't always have a good ping and fps are at 240, but my pc can't be compared with those of the pros, but sometimes everything feels very clean and you can edit quickly and then suddenly not the next day more where is something thanks for your help

sorry for the spelling I hurried

I don't play Fortnite, but some of my games depended on how much was working in the background and what the device was doing earlier.

It can really only be because of how heavily the internet or your pc are loaded, so if you now have 8 programs open on your pc, it could be that it does not react quickly. But otherwise I have no idea

But I have nothing open in the background