Change your quality preset in the advanced options of OBS
A faster preset means less charge on the CPU but worse quality
I recommend veryfast
Also use unlimited FPS limit, disable aero and try to use the cutting edge buid on osu with the "Reduce dropped frames" option enabled in the Renderer section
Lol did I wrote 5 GB Upload ? I meant 5 MB ;D
Also Window Capture has a really shitty Quallity, I want to do it with Game Capture for a good Streaming Quallity.
You need to configure it properly, I have perfect quality when I use window capture to stream.