1. You're using Windows 7 with Display Capture with Aero on. That's asking for a system to start crawling. Disable Aero, or use Game/Window capture, or (if you need Aero on and need to Capture your primary display, and it's available) use Game Capture and select the DWM option (but I don't know if that's available in Studio on Windows 7, you'll have to check and see).
2. OBS uses your GPU for compositing. You have a Quadro FX570, a VERY weak GPU that is woefully underspec'ed and doesn't fully support OpenGL 3.2+ or D3D11. This means parts of OBS might be running on your CPU, chewing up even more of the precious resource for compressing video and chewing up PCIe bus bandwidth with the data scuttle back and forth.
3. That's a Nehalem CPU, not a Sandy bridge (or later). Those are about 40% less efficient per clock than a Broadwell chip running multi-threaded+SSE code. So that 3.2GHz is really closer to 2.0GHz in modern CPU comparisons:
https://us.hardware.info/reviews/62...l-ivy-bridge-sandy-bridge-and-nehalem-results
Please note that those tests were done with HT disabled. It is known that Intel improved HT a good bit from Nehalem on the Sandy Bridge+ CPUs, so the gap can be even higher.