And, not only that, you can max the setting to literally as high as your comp will let them go, same goes for resolution, then once you compile the video, guess what, a video containing full res & settings, locked at 30 fps, no lower, no higher, so no lag.
However, using sourcerecorder to record your video, it'll be VERY laggy, it's the final video that won't have lag.
Lastly, i recommend turning the resolution, settings, and all that other stuff to lowest, windowed mode too, for making the demo, then, turn everything to max like i said above, then start the recording process.