That highlight looks absolutely fine to me. Smooth, no hitching. The broken aspect ratio is ugly but I know CS:GO players don't care about that.
However, I didn't notice earlier that you were running the game at such a low resolution. You have no reason to stream at 720p or use a 1080p base resolution, blowing up your content larger than the original won't improve quality at all. Set your base resolution in OBS to 1024x768 to match CS:GO and don't downscale and save some CPU cycles.