Hard drop frames in game after start obs

Hi, I recently bought a PC and started streaming League of Legends for my friends. Without streaming, I get around 280 FPS, but when I start streaming, it drops to 120 FPS, and I can feel the difference in gameplay quality. I’ve configured OBS following various tutorials, but I still only get around 120 FPS while streaming. Once, I managed to play one game at 180 FPS during a stream.

I’m using NVENC H.264 wherever possible and stream at 1280x720 at 30 FPS. However, I can’t use game capture because it causes League’s screen to freeze completely. Instead, I use window capture.

Here are my specs: • CPU: i5-14600K • RAM: DDR5 32GB • GPU: RTX 4060 Ti 8GB • Storage: 1000GB M.2 PCIe • OS: Windows 11

Can someone experienced help me figure out what I might be doing wrong? I can send more screenshots of my settings in private.