Disable Win10 Game DVR.
Remove monitor_capture from your scene, as game_capture is performing way better and it's better to not add/mix multiple game/display capture sources in the scene.
Use a quality based, variable bitrate encoder option (CQP with a quality value of 14-19 should be fine).
And I would recommend to use the limited YUV colorspace, instead of full. Depending on the video-playback software (or video editing software), full color space can some times be displayed too dark.
If you've done that and you still get massiv rendering lag in OBS (log shows "Number of lagged frames due to rendering lag/stalls: 2212 (30.1%)"), than you might have a GPU bottleneck (which should only occur, if you dont's use an FPS limit for your game, or with slow graphics cards).
Make sure, the GPU is never hitting over 95% load, to ensure some power is left to render your OBS scene.