There are 2 possible causes.
1. Bitrate- looking at your logs, your bitrate is set to 1500. It is inadequate for getting smooth picture whenever you move. Increase the bitrate to about 3000 and it should improve
2. X264 preset- faster presets tend to cause issues with pixellation whenever there is movement because the encoder can't estimate the motion as well as with slower presets and looking at your CPU, your computer should be able to handle lower presets.
Try the "fast" preset which, alongside with the bitrate increase, fix the pixellation issue