Ancient CPU for computationally demanding real-time video encoding... though with other errors in log not sure if CPU contention elsewhere is preventing render/encoding lag (as no frames to process), or your setup is actually adequate...
though trying color correction on such a CPU... seems like a stretch, but not my area. I tried to do less when I first started with OBS, with a 2 generation newer CPU, and similar GPU... and failed as CPU simply was overloaded.
So, my recommendations on quick glance, and not being a gamer, would be
- going through the log and fixing a bunch of the 'failed to open' errors... they can't be helping
this includes the audio-capture failed to load issue you have
- dropping to 30fps until you get the system stable and functioning, then testing with increasing fps or other settings
- don't use computationally intensive filters/effects (like chroma-keying,
- real-time monitor your hardware resource (CPU, GPU, RAM, Disk I/O, etc) usage