You're using the AMF encoder, so encoding overload error is your GPU, not your CPU.
Also, the repeated notices in the log of increasing audio buffering is an indication of system overload or some other problem-- it seems to be associated with you using an iOS device as a webcam. There seem to be a LOT of errors in your log associated with this plugin.
11:54:07.080: Output 'adv_stream': Number of lagged frames due to rendering lag/stalls: 624 (4.5%)
Rendering lag caused by GPU overload.
https://obsproject.com/wiki/GPU-overload-issues
11:54:07.103: Video stopped, number of skipped frames due to encoding lag: 12359/13973 (88.4%)
Significant encoder overload from the AMF encoder (your AMD card).
General Performance and Encoding Issues
