Stream and gamble with a PC but what should I upgrade?

The problem is that when I'm streaming, mostly fortnite, it does not feel as fluid as when I'm not streaming. I stream over streamlabs to 720 and the cpu is not overloaded when i watched streaming and zapping so i got about 43 by 48% so it always fluctuates. I do not know what I should upgrade the most, either the graka or the processor. What makes more sense to me? And my upload is not 9000 kbit. But soon I have a 100k line. But that's not it

PC:

AMD Ryzen 5 2600

Rx 580 8gb

MSI B450M

500w power supply be quiet

16 GB ram

SSD 240gb

1GB Toshiba hard drive

First the internet, then the processor to a 7200x and at the end vlt ne Capturecard so you save power