Atmospheric Archgun ammo-related slowdown

[Steel_Rook]

I've noticed that my framerate drops substantially when using an Atmospheric Archgun, seemingly in relation to how long I've used it. It either has to do with how close I am to using up all of its ammo with greater slowdown the lower I am, or else with some kind of persistent visual effect that keeps rendering even after I've stopped firing. The weapon I've found this to be the case with was the Imperator Vandal equipped with an Ammo Chain and Sabo Rounds, both max rank. I tried this both in the Infested Corpus tileset and when fighting the Profit-Taker Orb. It seemed like fighting in a location would drop my framerate from my stable 120 down to 80, then 60, then eventually 40 before I was forced to leave. Looking at the area where I'd been fighting would maintain the lower FPS, but moving to a different area seems to return me to a stable 120 FPS.

[Steel_Rook]

*Update*
Having experimented with this some more, I suspect it might be the "bullet hole" decals causing this issue. Because the Imperator Vandal is a naturally very fast-firing weapon with a massive ammo reserve AND 60% multishot chance AND penetration from Sabot Rounds (in my build, anyway), it tends to create a lot of bullet holes in terrain, which I suspect might be causing an issue. That would be consistent with my performance degrading the longer I fire the weapon and staying bad when I switch away from it, but improving when I move to a new area.

[bluejello]

I have seen similar issues with the imperator vandal in both normal missions and arch-wing missions (normal imperator as well in the archwing mission, don't have it gravimodded for regular ones)
Framerate drop continued after the decals despawned when I tested in the simulacrum.  I did not see similar issue with the gattler when I tested it in the simulacrum, nor with the soma or gorgon.