I know nothing about computers, I need help

My pc is 5 years old, and gaming and live streaming is starting to slow down (not editing softwares though, for some reason)

here's some specs, idk what is what so if you give info on other devices are called I can try to find them

intel i5-9600K

bios is american megatrends (2019)

NVIDIA GeForce RTX 2050

my computer has 317GB free of 445 on C disk

most stuff and apps are stored in D; 1,30TB free of 1,81TB

mother board (Or I guess it's a motherboard), is MPG Z390 GAMING EDGE AC (version 2.0)