Stream Upgrades

Hello, I'm decently new to PC but I have been streaming for a while. Usually I stream COD on console but I've been trying to stream H1Z1 but whenever I do I lag really bad (doors take longer to open, minor frame drop, etc). I was wondering what I should upgrade on my PC to fix this. I have- Intel i5 6500 processor 8 GB Ram Geforce 750 Ti Gigabyte Intel B150M-DS3H motherboard If I had to guess it would be my graphics card but I'm not 100%