Problems Recording Videos

When I try to record, using either of the recording software packages listed above, while playing Minecraft 1.14.1 Pre-Release 2, everything begins (literally) stuttering, within about 10 seconds, and finally just comes to a stop. If I can move at all, the lag is terrible, AND...I begin to float around above the surface of the world, as if I'm in Creative Mode, when I'm clearly in Survival Mode. Within minutes, I have to quit the game, and I end up NOT being able to quit the recording software correctly, and then I have to restart my computer.

I have never seen anything like this before, with any version of Minecraft! What on Earth?

I get some lag in 1.14 Official, but my recording has been fine.

I can duplicate this and send an AVI file, if necessary. At this moment, I have none, since I emptied my trash bin without thinking, after the last time it happened.