Question Random Lighting Bug - Artifacts and slowdown

Hi all, I am experiencing a rather random bug in my project. I cant seem to reproduce it consistently, but its happened a few times now. I'm trying to nail down exactly what causes it, but its got something to do with firing and swapping weapons. This video shows what happens:

As you can see the lighting becomes completely artifacted, and the game slows to a crawl making it impossible to play. Even when I pause the game, which sets the Time Scale to 0, the lighting still seems to be jittering/moving. This happens both in-editor and standalone.

(Im currently trying to reproduce it while I have the profiler open, but it doesnt seem to want to pop up again for the time being.)

I only have a single directional light in my scene, but bullet hits will randomly create a point light, and then fade out and destroy themselves within half a second. The point lights do not cast shadows and have volumetrics turned off. I've disabled the bullet hit light effects and still get the bug, so I'm assuming its not that, but though't I'd mention it.

Below are the light settings for my directional light, scene, and bullet hit point lights.



I am just bamboozled by this. In a desperate attempt to try anything, I thought it might be the amount of bulletholes I was spawning - upwards of 50 on screen at a time - so I've reduced that to 10. Same with bulletcases, which are non-kinematic until they have <0.1 velocity, I reduced to 10 max.

Also I am on Unity version: 2019.2.17f1. I'll make a backup of my project and try updating and see if that helps.

Edit: I updated to Unity 2019.2.19f1, and its running HDRP version 6.9.2. Haven't encountered the bug again since making this post. But I'll keep trying.

Any and all input would be very welcome.

Cheers,
Brendan